Hi Mick from another new comer, I am also building the "Will" and not far behind you, so, have been following with interest.
Re your unidentified parts, post, 18th January, it is the engine throttle controland, if you look very carefully at drawing sheet 1, you will see a small square between the compass binicle and engine hatch, thats it.
It took me ages to find it and I haven't worked out how tall it should be yet, I guess a little taller than the compass.
Hope this helps as I agree with everyone elses views of Billings instructions.
Good luck with it and if I can help further I will jump in.
Also good luck with your health, I know how hard it can be.