A few questions from a new '91 300E owner

Just purchased a '91 300E that I really love. This is my fourth and newest Benz and I'm really excited about it. A few puzzling little quirks I thought I might post about:

1. My power antenna. When it goes up, it goes up, but it doesn't seem to know to stop. Motor just keeps running for 10 seconds or so and then finally stops. When it goes down, it goes down about half way and then gets stuck. Again, motor keeps running for an unhealthy 10 seconds and then finally stops. Antenna will only go down if I push on it while the motor is still running.

2. Climate control. Every once in a while there is a rattling noise coming from inside the dash around the climate control area. Kind of sounds like it is not off all the way. Fiddling with the climate control buttons sometimes helps, sometimes doesn't. Also, the lights that light up the climate control buttons only seem to work if I turn up my dash lights all the way, which is a bit on the bright side.

3. Stereo. I really love the original Mercedes stereo it has with the big knobby control buttons and the fact that it says Mercedes-Benz on it, etc. However, I'm wondering if I can't find another similar original stereo but one with a CD player that would fit?

Thanks in advance for any advice you can provide!