CA can be used, but use the one that has a slower cure. Or if you really have patience and is ready to expend lots but also get a strong joint epoxy will do.

To increase the roll rate increasing the deflections will work too without having to mod the plane. I did this to my trainer and it really improved. 1/2 more throw at the aileron the the roll rate doubled.

Also, sometimes it may be better to build another aileron or rudder to the spec you want.

Hope this helps....