If 85% of the class withdrew or failed, I think you have a good shot at getting back up to speed when it comes to that (and the first F will just be on your freshman record.. which to advisors is usually not incredibly huge). The TA stuff is good, the GPA could be a lot better (especially if you go to a lower end school). If you can rock bio and o-chem and make your MCAT good, and get published or something, I bet you could get a good shot at it and get into a low tier MD.