Alright, so, bone and muscle strength are obviously a must. Though if you have inherently brittle bones, I wouldn't recommend tricking to begin with. Muscle strength is handy, but you'd want to focus on core strength to get most rotation-centric tricks pat down. Leg muscles too perhaps, if you're a little thick on the side and still want to get in on that tricking action.

Depends on what you consider enough. If say, you want to do aerials and not fuck up most of the time, you'd want to be able to do a rather wide split, etc etc.

mmmmm, i'd say yes based on experience, but you'd want to do your own research on that