1997 Mercedes E320

Two questions

1. When my car is in idle for 5-10 minutes, the engine thermometer rises and the a/c starts to blow hot air. However, when the car gets moving, the a/c is fine and the temp goes back down to normal. This is really annoying when I am sitting in traffic.

2. My A/C will not blow higher than medium. A/C still takes a while to cool as well.

Any ideas? Is this a cheap fix?

Thanks.