Bumper cover/antenna/door lock questions

Hello all,

I am new to this site and new to Mercedes ownership, and I am looking forward learning a lot here. And now I have a few questions about the 1989 300E I had just recently acquired.

1. There is some damage to the front bumper cover and I would like to replace it. How do I do this? What tools do I need for the job? Does it make a different if I use an aftermarket parts or and official Mercedes parts here?

2. The antenna sticks -- it does not want to go up when I press the antenna dashboard button. Would it need to be replaced and how would I do it? Seeing that it located on the rear fender, it looks as though I would not have a hard time getting at it. But what other issues would be involved or what other options should I consider?

3. The door lock on the driver side does not work properly. I can lock the door on the outside with my key, but I cannot press the button on the inside. What could I do to fix this?

Anyway, I hope the questions are not too basic; and thank you in advance for whatever help is given.

Sincerely,
Gary Vandenbosch