RE: servo strength
Do a google for "servo load calculator" and you'll get hits that take you to a couple of online calculator sites. Input the size, speed and max deflection angle and it tells you how many inch-ounces of torque it needs. But do not spec your servos with that number. If you do they will be running very close to their stall load and that's not good for the internals. Instead take that number from the calculator and double it and look for servos of that strength. That way you're running well within the servo's comfort range and not on the edge where you're risking a failure that could cost you an airplane.