I have used the Hitec micro servos in the ailerons on race planes but the ailerons aren't used very much so I have gotten away with it. On these planes the ailerons are pretty small strip type and don't require much movement. Micro servos can have the same torque as a standard size but you have to keep in mind the motors are only half the size too so the bigger controls will put more load on the motor.
On your plane it is more common to use flaps instead of flaperons. I use the flaperons on one of my fun fly planes and have them slaved to the elevator. As the plane slows down and I start adding up elevator the ailerons start to come down. The problem with the flaperons is the plane will want to tip stall as it looses the lift when slowing down. If you haven't used them before take the plane up high and play with them so you have plenty of sky so you can turn them off and get the plane back under control. They are fun to play with on windy days. On calm days the plane wants to stall more. Trainer type of planes aren't the best type to use flaperons with. I have more fun with a trainer using flaps. I just cut the ailerons about on third and make the flaps.
Picking servos is just something most of us have learned over time. Weight of the plane, size of the controls, type of plane. I have never used a chart but they may be of great help?
I have built a couple of the Gentle Lady kits and just used micro servos, the HS 81s. Even with an electric motor they don't require a lot of power for control operation. I think they only cost $9.00. The motor and pot don't like the vibration from an engine but I have gotten away with using them for the throttle without problems. Luck??