I replaced TOOTH with MOUTH on most bite attacks, dunno why I didn't do it on olm ponies, must be a random derp. As for nails and talons, thing is, I thought I'd been pretty thorough in removing related tags. It worked with penguin ponies, I just don't know what I've forgotten to remove.
Most ponies live in tree cities by default, yes. I'm going to switch that up in the next version, since world gen seems to have trouble placing all of them. Ponies and zebras live in tree cities, cave ponies live in detailed caves, like dwarves, diomedians in dark fortresses.
Yes, there will be animal ponies. I've made pony variants of all the vanilla ones, and added [DOES_NOT_EXIST] to the vanilla animal men, through the animal person variation where possible to reduce the mod's footprint. I've also added a few more animal ponies, things like various bear ponies, phantom slippy ponies and honey badger pegasi(well, it's too easy right now, isn't it?).