1979 BMW 320i help

I have a 1979 BMW 320i that I recently bought and have been working on. There are a few things I'm not sure about. First, when I first turn it on, it idles kind of rough until it warms up. Second, if I let it idle for a while the temperature gauge starts to show that it is overheating, but when I start driving it goes back down to normal. Also, if I were to turn on a fan or something it would raise the temperature gauge. I also have a subwoofer in my car, and when ever I would have my radio on, the temperature gauge would move up and down a bunch whenever the base would hit. The last thing is that, I found out the my AC didn't have a belt on it, so I went and got one and put it on it last night, and i drove it down the road with to see if the ac worked. While doing this the temperature gauge showed that it was overheating as long as the ac was on.


Also, it is a 4 speed, and it is hard to put it into and out of reverse. Also, when I go to put it into first, it sometimes wants to take off even when the clutch is all the way to the floor. When driving, second, third, and fourth are fine. No problems. Another thing I noticed is that if I have the clutch down to the floor and in gear, I can't keep it there long without it dying on me.