Nix the outer flap idea. You get the most leverage out at the tips. You would loose too much aileron authority with the flaps out there. You could use the inner 1/3 of the aileron as your flap. 4 servo's would work great. You could use a computer radio and mix the flaps back in and still have full aileron operation untill you activate the flaps. And finally you want the flaps inboard because they really do not care where they are in the airstream. I am not sure but it would also help in lowering the stall point inboard.

I agree with a nice Saito 90 in the nose. You could use it later on in one of your models. I would hesitate on the 100. But it probably would be the best choice for the future. You would possibly run out of prop clearance with it though. Good luck with it.

Mark Shuman