You hit the surface deflection right on. It can be judged as the distance the outer edge (opposite from the hinges) of the control surface moves from the center to each end of its throw. As for torque, that's one of the ways to tell the power of a servo. An average servo has a tourque of about 50 ounce-inches. This means that at 1 inch out on the arm from the pivot of the servo, it can move--or at least hold--50oz of weight. Adjusting which hole on the control horn that is used will change the amount of deflection you get. The closer the hole is to the hinge of the control surface, the more deflection you will have. If you want a more detailed description, let me know. I could fill you in on the geometry of it if you don't know about it yet.

Silent J