The ailerons have very little chord. They only deflect about 10mm up and 10mm down. I use one standard servo and mine will roll very fast. I usually fly most of the flight with the dual rate switch for ailerons on low rate. If the HT645 is a standard, it'll do excellent.

It should climb out of sight, no problem. However, if by hovering, you mean hanging nose-up on the prop, that takes fairly large surfaces and the .46 Ultimate wasn't designed with those. My OS.46AX will pull it off the ground in a heartbeat and pull it out of sight, accelerating as it goes, but I've yet to be able to hold it steady, nose-up. I can land it at a walk, so the surfaces work well with airspeed and wind over them, but they're not big enough to do 3D stuff where the prop blast does the work.