RE: Futaba Receivers & Servos for SIG Wonder
A 15 2-stroke is plenty. In fact, I think a 15 would be ideal. I had one with a 25 and it was a lot more weight than it needed.
Either Rx would work, but I prefer the R617FS.
Any of the servos will also work. You don't need anything fancy. Standard, nylon-geared servos will work fine. I think mine had S3003's in it.