You will need at least the servos and one of those cheap servo centring tools, they can be set up to run off 4AA batteries. You centre the servos with it so that the ones inside the fuselage will work the elevator and rudder equally. Then you can add the elevator servos to the wing. You can add the battery, esc, motors and receiver later. The servo tester will also allow you to test the controls using the pot on it to move them.
I would build the simple scout as a 4ch. If you are making the mini scout the same applies with the servos but obviously there’s no elevators to do.
The Simple Stick is way way easier than the scout. The Tiny Trainer is also easier, no turtle decks on either of them and a separate wing is better both for crashing/rebuilding and ease of transport.