Yes mouse hovers should be avoided. If you want on this button have a click toggle through all three states in order and leave the mouse hover for direct choice, therefore both usage patterns would work.
No matter what Adobe says CS5.5 is just CS5 with Acrobat 10 instead of 9 and all of the patches applied to the other software. They were not going to release a new CS with Acrobat 10 until CS6 but a lot of people bitched about it and they came out with 5.5. So since there is no real difference between PS 5 and 5.5 they should support it.