Are the new Wave2 AP3935 APs compatible with the older C25 controllers? I would assume they are compatible with recent firmware on the controller, but I'm not finding documentation that mentions whether they are or not.
Yes they are. The controller release notes is where you find the answer. It will list the particular model AP's as supported AP's. If you don't see the AP listed you need to upgrade higher. If memory serves me correctly the V10 code is when they were added.