If she works for you get her, but this seems like a horse that would do very well in things you aren't interested in and do "ok" at a fun/local show level for the stuff you do want. If you love her get her, but I would pass and look for something that would work for you. I don't know if it's fair to you or the horse, but I guess as long as you're both happy that's what is important. I'm still not sure what your logic is on wanting a TB.
Re issues- I don't like that back end, but doesn't sound like you'll be doing anything remotely strenuous so wouldn't worry too much as long as she passes a PPE.
I really don't see a trail horse here but that really is a temperament thing. I would guess she doesn't have it, but absolutely no way of knowing without trying. Also depends on your skill as a rider and what you are looking for (something that walks in a straight line until told otherwise or something you ride even if it is just on the trails).
Shrug, if you love her go try her. No reason not to, though I'm not seeing a match here in any way, but I'm some random person on the internet.