I assume Avis was notified by the "Polizeipräsident in Berlin" (Berlin Police Commissioner) that a certain car registered for Avis was involved in this administrative offense. Avis was (in writing) questioned as witnesses and informed them that you had been the driver. As a matter of courtesy (and to justify to 11 Dollars), Avis informed you.

I assume you are based in the US. Given that, I would not expect any further action because they most likely close the file.

However, if not:

1.) You will get the ticket either in the mail send by "Polizeipräsident in Berlin" (the incorrect way) or via Federal Authorities conveying it to State Authorities conveying to to your local police (the correct way and the reason you most likely will not hear about it again)

2.) If the traffic light hadn't turned red for longer than a second, there is a flat fine of 50 Euro, otherwise 125 Euro. This can be doubled for foreigners because you do not face the further nasty consequences effecting your license (one month vacation from driving and an entry in our license file)

3.) Bank transfer

4.) Yes, but what do you expect to gain? However, appeal will he heard at one of the Berlin local courts. You can either instruct a lawyer of defend yourself. Be prepared that the judge can instruct you to come (if you - in this instance - do not appear, the appeal will be dismissed).

5.) Most likely nothing.

I hope this helps. My fee note will follow. I accept beer, miles and points

Cheers
Thomas