It is my understanding that:
A) a servo wheel turns about 90 degrees;
B) the more overall rotation of the servo arm the greater the resolution of the control;
C) more up than down is preferred for the aileron;
D) little or no down aileron with mostly up is preferred in a model, to help prevent stall out and diving in opposite direction to control input.

Questions: If above statements are correct (comments please), what is the affect of mounting the servo arm at positions other than at 90 degrees to the hinge line?
The star arms furnished have different offsets (Thanks Minn Flyer) and a straight arm could be adjusted for greater amounts.

I would like to understand which direction would accomplish more up than down.

Would this not also help in setting up flaps, but in reverse?