No way to be sure until you look about the stator cooling kit. Some have found them already installed when they didn't expect it. I belive many moons ago Yammy issued a service bulletin on that problem. Some were taken care of, some not.
Hopefully the second gear problem will not show up for a while. It depends a lot on the way it was ridden by previous owners. My '84 was a one owner bike when I got it at about 30 something thousand miles from a older rider that toured with his wife on it. I'm at almost 68,000 miles now and hasn't popped out yet. If you're strongly mechanically inclined it can be a DIY project. You have to pull the motor and split the case but if you're brave.........
A few threads around here on the subject. Been done a few times and a good chance to do some other improvments at the same time.
The four brush stater is a good upgrade to start out with. Major improvement in cranking power. As the summer comes on you'll find out why.