I have a 1987 Fiero GT

I have a 1987 Fiero GT. It should go without saying that I often have mechanical problems with it. When I bought the car, the gears would grind quite a bit, especially in putting it into reverse. I replaced the master cylinder and the slave cylinder, but that is about as far as my mechanical knowledge goes. That was about two months ago and it seemed to do the trick. However, I noticed recently there has been a large amount of fluid leaking from the tranny. I drove home (about 50 miles) and it was in fifth gear when it popped out of gear and scared the hell out of me. It did this about five more times on the way home. Then, when I was driving back to my other home, it was occurring more frequently, so I drove it in fourth gear most of the way back. I parked it and the next morning, I went out to drive to work, but it was close to impossible to get into any gear. I finally got it into first gear, but when I let go of the clutch, it was bogging down and died (did not move) I tried about three more times, the last time, ti jumped forward instead of a slow movement, so I parked it and rode the motorcycle to work. Any help on this would be much appreciated. I want to take it to a shop, but I want to know what I am talking about when I get there so I can avoid any confusion, unnecessary costs, and save some time. PLEASE HELP! Thanks