pretty sure you can change the 4 th gear hub in the car, and the rack would be a good idea to do at the same time while the cradle is off the car, the rack is just hanging there asking to be swapped out.

sounds like you got through a few hurdles, whats a few more? fix it up a bit more then sell it or keep it. you can get more if its all running right.

a/c, well you know how that can go, find the leak, try to seal it or replace what ever is leaking. shops charge a arm and a leg.