Tim,

if you're building wings/stabs with foam, don't join anything until each panel is 100% finished - you'll be glad you did. And yes, do build the wing and stab first. I usually start with the stab as a warm up. I'd also recommend that you do all the gear prep work on the wing panels prior to sheeting them. Jim is doing a Tiporare build from a Eureka kit over in the kit building forum. His pics might help in the setup of the wing for retracts and the servos. You'll likely want to mount the aileron servos just outboard of the retracts. If you put them behind the LG and one fails, that servo will likely be damaged unless it is recessed into the wing. That form of installation is something you might want to consider but it is more work than installing them upright.

Also, you don't need retract servos in the wing unless they are mechanical. With pneumatic (air) Robart's, all your retract stuff goes in the fuse (it doesn't have to but it is convenient). You will need three servos in the wing (all three can be the same) for each aileron and flaps (this servo goes centered in the wing top) and four servos in the fuse (rudder, elevator, throttle and retract). I suggest that you use mini or micro servos for the throttle and retract. They can be laid out as a quartet with the rudder/elevator in the rear and the throttle/retract in the front. Receiver in front of them and battery in front of that. Tank on a plate as low as possible allowing the retract to be installed. Because your engine is side mounted, you want the tank to be as low as possible so its center line is close to the carb level.

David.