Jaager

I was thinking about your wale bending task.  Bending thru the thick dimension is fighting what the wood wants to do.  But would it be easier to bend a 1/4" x 1/16"?
I was shocked by kits doing wales by superimposing a half thickness wale over the complete first layer planking with a double layer hull POB. If the wale is two layers, the evidence would be hidden by the planking strakes above and below. It is heretical, but you could pretend that the hull is being girdled. 

I did some more armchair experimenting:
Would it help to use cardboard that is close to plank thickness?
Would it help to use a penetrating treatment with a varnish on both sides to stiffen it?
Would a plastic sheet that is thick enough to be stiff, but thin enough to cut with a sharp violin type knife and straight edge work better?
Once the pattern is refined to make a good fit, it can be transferred to two layers of planking stock bonded with something like double sided tape.  This way P&S planking can be spilled together.  About half the work and a better likelihood of bilateral symmetry?
 

Mark,
When you measure out a plank, do you first transfer that to a mock up from something like poster board to check the fit, before actually cutting wood?

Hazel -- from what I can find from the Wood Database - this looks to be a promising species
Pacific Dogwood - if it is similar to Cornus florida - our state flower - you have something special - great for carvings, delicate or strength wanted deck furniture - blocks, deadeyes - do not waste it on parts like frames, beams, planking - unless your supply of it is large and limitless.
Crab Apple -  most any fruit wood is more than excellent.  I consider Apple to be a king.  It is just difficult for me to source.
Yew  -  They do or did make a vary toxic chemo agent from this - I suggest that getting up close and personal with it is not a good idea
Viburnum  -  not a clue, I would have to see it.  But, I see arrow wood as a characteristic associated with it.  Was it  the Apache who used reeds?  Straight, light weight, and had hollow point characteristics on impact?   If it is pithy I would stay away.  For spars, dowels are subject to problems, I would be cautious with a rod that Nature made, no matter how straight.
Juniper - if it is similar to our Red Cedar - I would not use it.
 
Frame spacing -  there is no simple answer - there are no rules pf the sort that you are seeking.  It pretty much varied from ship to ship. There were fads, even with the RN.  It could be seriously different at 20 year intervals.  The RN was down right peculiar and obsessively detailed in their framing.  But not at all predictable from ship class to ship class in what those details were.
There is another factor in play: POF scratch modelers.  If a model has frames showing, unless it was a classroom engineering model or a tech demo model, there is a good chance that the framing is stylized.  It was probably built to show off the frames.  The actual frames were probably so close together that they would be quite unattractive to display.
 
From your questions, I am guessing that you are just now dipping your toe into all this.
Any sailing warship of the line is difficult slog for the most skilled of us.  HMS Leopard  is not as overwhelming  as Victory or Sovereign, but it is a huge bite. 
In your place, I would begin with something much smaller.  I would do POF, but totally plank the outside and the deck.  I would wait until I had a much deeper understanding of this complex subject and a lot of build experience before attempting to build a model showing the guts of the thing.
 
But to clarify where I am coming from:  I am much attracted to open framing below the wale - My favorite is the stylized 17th century Navy Board.
The framing above the wale is about as interesting to me as 2x4 house framing.  I think it mostly had the same utilitarian function. To me it is pug ugly.  I am also not all that enamored with omitting desk planking either.

The focus  with this is limited to a few countries in the 17th, and 18th and early 19th centuries as far as giving up and surrendering as opposed to a fight to the death.   I have made no effort to catalog the various wars, but in general the following situation seems to hold:  The conflicts were largely economic disagreements,  the men in combat were generally from an economic class with no political power and of no actual concern of those in power and generally seen as disposable,  the officers were 2nd or 3rd sons who would otherwise be an economic drain on their families, and the countries in conflict were essentially cousins.  It was more of a sport than a life or death cultural conflict.   These factors were totally different in the 20th century. 

The focus  with this is limited to a few countries in the 17th, and 18th and early 19th centuries as far as giving up and surrendering as opposed to a fight to the death.   I have made no effort to catalog the various wars, but in general the following situation seems to hold:  The conflicts were largely economic disagreements,  the men in combat were generally from an economic class with no political power and of no actual concern of those in power and generally seen as disposable,  the officers were 2nd or 3rd sons who would otherwise be an economic drain on their families, and the countries in conflict were essentially cousins.  It was more of a sport than a life or death cultural conflict.   These factors were totally different in the 20th century. 

The focus  with this is limited to a few countries in the 17th, and 18th and early 19th centuries as far as giving up and surrendering as opposed to a fight to the death.   I have made no effort to catalog the various wars, but in general the following situation seems to hold:  The conflicts were largely economic disagreements,  the men in combat were generally from an economic class with no political power and of no actual concern of those in power and generally seen as disposable,  the officers were 2nd or 3rd sons who would otherwise be an economic drain on their families, and the countries in conflict were essentially cousins.  It was more of a sport than a life or death cultural conflict.   These factors were totally different in the 20th century. 

I did my usual process of imagining a theoretical way to approach your problem:  bars of polishing compound with a gradation of every finer grit - attaching pieces of leather or shammy leather to a disc - maybe using the DIY hook and loop as a way to attach, go at it with a rotary tool.  -AND - I decided that I would probably skip all of that work and go to a glass shop and have them cut me a piece of mirror to the size that I needed.  Glass should stand up to time better than SS.

I did my usual process of imagining a theoretical way to approach your problem:  bars of polishing compound with a gradation of every finer grit - attaching pieces of leather or shammy leather to a disc - maybe using the DIY hook and loop as a way to attach, go at it with a rotary tool.  -AND - I decided that I would probably skip all of that work and go to a glass shop and have them cut me a piece of mirror to the size that I needed.  Glass should stand up to time better than SS.

I did my usual process of imagining a theoretical way to approach your problem:  bars of polishing compound with a gradation of every finer grit - attaching pieces of leather or shammy leather to a disc - maybe using the DIY hook and loop as a way to attach, go at it with a rotary tool.  -AND - I decided that I would probably skip all of that work and go to a glass shop and have them cut me a piece of mirror to the size that I needed.  Glass should stand up to time better than SS.

I guess I am just unlucky, but my Brother unit requires anything scanned to be scaled up 102.5%.
I used a transparent metric ruler as a scan object and print out check.
I also had to set a canvas size in Painter that does not give or entice Windows Photo Viewer to "adjust" the size of a document to be printed.  Having the border thing checked by default is an extra click that I have to always pay attention to.

Home scanners have a scale distortion factor - my guess - to make copying paper currency more difficult.
ANYWAY, if you wish a scan to print out an exact copy of the original, the scale distortion factor for your specific machine needs to be determined.  It is a constant, so determining it once is enough.  Just be sure to document it.
 
Guys here write that commercial blueprint operations provide an exact 1:1 copy.  I used a company for a NMM print color scan.  They do signs and advertising.  The color PDF - while good, also needed to be reduced to 70% to match the original.
 
There is also a "maybe" method - it did not work well enough for me - inkjet(?) print on a sheet of paper with wax/plastic coating on one side and iron that directly onto the wood.  Probably works better for scroll cutting cartoons - something without a lot of detail.

I attach a lot of patterns.  I need the patterns to stand up to abuse.  I use BestTest rubber cement - because I get it in pints or quarts, I also have Bestine (n-heptane) to keep it at brushing consistency.
The main trick is to use a liberal coat on both surfaces - let the thinner evaporate - then place the pattern.  It is a "get it right the first time" situation.  There is no fine tuning of the position.  Any brand name rubber cement should serve your need.  It is false economy to go generic though.
 
Long ago, before the Internet, before there was help, I used PVA for a model.  I did not know about isopropanol  being the reverse agent.  I used sandpaper to remove the pattern.  That was a serious amount of work.  But there was no problem with the pattern moving or popping up.
 

I guess I am just unlucky, but my Brother unit requires anything scanned to be scaled up 102.5%.
I used a transparent metric ruler as a scan object and print out check.
I also had to set a canvas size in Painter that does not give or entice Windows Photo Viewer to "adjust" the size of a document to be printed.  Having the border thing checked by default is an extra click that I have to always pay attention to.

Home scanners have a scale distortion factor - my guess - to make copying paper currency more difficult.
ANYWAY, if you wish a scan to print out an exact copy of the original, the scale distortion factor for your specific machine needs to be determined.  It is a constant, so determining it once is enough.  Just be sure to document it.
 
Guys here write that commercial blueprint operations provide an exact 1:1 copy.  I used a company for a NMM print color scan.  They do signs and advertising.  The color PDF - while good, also needed to be reduced to 70% to match the original.
 
There is also a "maybe" method - it did not work well enough for me - inkjet(?) print on a sheet of paper with wax/plastic coating on one side and iron that directly onto the wood.  Probably works better for scroll cutting cartoons - something without a lot of detail.

I attach a lot of patterns.  I need the patterns to stand up to abuse.  I use BestTest rubber cement - because I get it in pints or quarts, I also have Bestine (n-heptane) to keep it at brushing consistency.
The main trick is to use a liberal coat on both surfaces - let the thinner evaporate - then place the pattern.  It is a "get it right the first time" situation.  There is no fine tuning of the position.  Any brand name rubber cement should serve your need.  It is false economy to go generic though.
 
Long ago, before the Internet, before there was help, I used PVA for a model.  I did not know about isopropanol  being the reverse agent.  I used sandpaper to remove the pattern.  That was a serious amount of work.  But there was no problem with the pattern moving or popping up.
 

Home scanners have a scale distortion factor - my guess - to make copying paper currency more difficult.
ANYWAY, if you wish a scan to print out an exact copy of the original, the scale distortion factor for your specific machine needs to be determined.  It is a constant, so determining it once is enough.  Just be sure to document it.
 
Guys here write that commercial blueprint operations provide an exact 1:1 copy.  I used a company for a NMM print color scan.  They do signs and advertising.  The color PDF - while good, also needed to be reduced to 70% to match the original.
 
There is also a "maybe" method - it did not work well enough for me - inkjet(?) print on a sheet of paper with wax/plastic coating on one side and iron that directly onto the wood.  Probably works better for scroll cutting cartoons - something without a lot of detail.

I attach a lot of patterns.  I need the patterns to stand up to abuse.  I use BestTest rubber cement - because I get it in pints or quarts, I also have Bestine (n-heptane) to keep it at brushing consistency.
The main trick is to use a liberal coat on both surfaces - let the thinner evaporate - then place the pattern.  It is a "get it right the first time" situation.  There is no fine tuning of the position.  Any brand name rubber cement should serve your need.  It is false economy to go generic though.
 
Long ago, before the Internet, before there was help, I used PVA for a model.  I did not know about isopropanol  being the reverse agent.  I used sandpaper to remove the pattern.  That was a serious amount of work.  But there was no problem with the pattern moving or popping up.
 

For context: I'm still building my first model ship (Artesania's viking ship) and I'm designing my first unambitious original model ... but I know a thing or two about laser cutters. Just a thing or two, mind -- I make no claims at expertise. I'm a teacher and have an Emblaser 2 in my classroom. The (primary) students and I use InkScape to design things, and then cut them out of laser-grade plywood.

Some thoughts:
 
- Everything everyone else said is true;
- I think InkScape (open source/free) will do the job, but be prepared to learn it -- and the cutting process itself -- through trial and error;
- Cardstock is a nice way to trial cuts without wasting expensive plywood;
- Desktop units, including my Emblaser, have limitations (the thicknesses of materials, the kinds of materials, etc) you'll need to work within;
- The very young students and I learnt through play, and you'll need to do the same -- as with kits, at some point you need to stop reading advice and just get stuck in.
 
In short, it's a commitment unto itself, above and beyond designing and assembling the model. If you're into that kind of thing -- and I am -- it's an enjoyable journey. If computers are a means to an end, you may be better off buying a scroll saw.
 
EDIT
 
In addition to the above, I think the best way to learn about laser cutters is trial and error. I encourage children to learn that way, as it's how I learn. For instance, in the past few days I cut some pieces for the model I've designed. I learnt a few things: the order in which you cut pieces matters a great deal. I mean, on some level that's obvious ... but for what I was doing, it wasn't obvious to my inexperienced brain. I also made the pieces a bit too thin. That's probably less to do with laser cutting and more to do with my lack of experience using store-bought kits ... but, still, the measurements on screen seemed okay, but the finished product was more fragile than what I hoped for. These mistakes are easy to correct in InkScape, but nonetheless chewed up a few sheets of plywood.
 
You'll also want to think about ventilation. The Emblaser comes with a hose you poke out the window, but if you're in some high-rise apartment building or somewhere bitterly cold you might need to pay for a filtration unit. I'm unfamiliar with other laser cutters, but I can't imagine they'd work any differently. 
 
One other thing that's cool, I guess, is you can cut other materials. For context, the model I'm making is a replica of my brother-in-law's fishing boat (an unambitious subject, but accessible ... and if it turns out half-way decent I'll pass the model onto him). The actual boat has carpeted flooring. The Emblaser is very happy to cut out felt. Now, a pair of scissors can do that, but there's no way my scissor-work will match the accuracy and low-effort-to-reward ratio of what the laser cutter can do in about two minutes. I can use the same image I made of the 'upper deck' (or whatever it'd be called on such a small craft) to cut out a 'carpet' that's precisely the same size. 

Is your type of PVA - yellow - which I prefer for wood to wood - or white PVA. 
The white seems the be water clear when it polymerizes.  The yellow is clear amber.
If you are using white - the darker color may match the wood when wet - which is the color it will be when a clear coat finish is applied.  (shellac for me). 
If you do a test - same wood - plus a patch with white PVA - and use you final clear coat on it, is the filler still darker than the wood?

I suspect that a private yard would use the stock that was available.  If they wasted material,  they would not stay in business.  In a model - it is ultimately a work of art - even if the goal is the focus on an exact replication of the micro level assembly.  I think the eye/mind craves symmetry.  An actual ship would probably be too large for a lack of bilateral symmetry to be observed.  The size of a model makes a lack of symmetry sort of stand out.
 
Going to school on the actual methods and techniques in extreme detail at the primary learning stage is wise and probably necessary.  But ultimately with a model, Art also has its demands.  Sturgeon's Law certainly applies to our efforts, but we should try for the ten percent.

Is your type of PVA - yellow - which I prefer for wood to wood - or white PVA. 
The white seems the be water clear when it polymerizes.  The yellow is clear amber.
If you are using white - the darker color may match the wood when wet - which is the color it will be when a clear coat finish is applied.  (shellac for me). 
If you do a test - same wood - plus a patch with white PVA - and use you final clear coat on it, is the filler still darker than the wood?

I suspect that a private yard would use the stock that was available.  If they wasted material,  they would not stay in business.  In a model - it is ultimately a work of art - even if the goal is the focus on an exact replication of the micro level assembly.  I think the eye/mind craves symmetry.  An actual ship would probably be too large for a lack of bilateral symmetry to be observed.  The size of a model makes a lack of symmetry sort of stand out.
 
Going to school on the actual methods and techniques in extreme detail at the primary learning stage is wise and probably necessary.  But ultimately with a model, Art also has its demands.  Sturgeon's Law certainly applies to our efforts, but we should try for the ten percent.

Neither species is one to use if there are other options.
The Ramin may actually be something else since it is on the endangered species list.
Basswood is just too soft and prone to splintering and rolling fibers - (friable?).
Its much better European brother ( Lime - Linden ) is still not that good a choice for planking.
 
The primary difficulty is that it is becoming increasingly difficult to source wood of suitable species that is in dimensions needed by an end user.
 
You live in a region with ready access to lumber of species that are excellent for our uses:
readily available:  Hard Maple, Black Cherry, Yellow Poplar
hit or miss: Beech, Birch
If you can be your own sawyer - most any fruit wood: Apple (the king), Peach, Pear (street planting ornamental too), Crab Apple, Plum.  Dogwood, Holly, Hornbeam, Hophornbeam, Hawthorn.
 
Avoid most any nut tree species - open pores and out of scale grain:  Walnut, Oak, Ash, Hickory.
 
It is the heat that allows bending.  The wood fiber glue (lignin) is not affected by water. The water raises the grain.  A bit of water as steam may transfer heat to the interior more quickly, but the time difference is probably of no practical significance.  The heat source must not be hot enough to char or even cook the wood.
 
Ships, and even larger boats, required more than one plank per strake, which avoids having a single plank having an opposite twist at each end.  Lateral bending ( thru the thick dimension ) is best solved by spilling the plank instead.
 

You may find it convenient to get a Rogers drill bit stand to start with.  Then restock using bulk single size in 10's of the numbers that are getting use.