Presentation and the first questions about the 90s V8

Hello.
first of all I am 31 years old from Herdorf (near Siegen). Screw VW T3 buses, now it should be a V8 since I stumbled over the Audi and bought a 1990s 3.6 this has 295,000km on the clock. Of course he's got a few poops, but you can get rid of them.
Since I'm newcomer to the audi world of V8, please excuse stupid questions.
Now I have a small service so spark plugs new, oil + filter and air filter new. Gear oil I change days.

Now to my questions.

The good has speed fluctuations in the stationary gas here the speeds vary between 500 and 750 revolutions. Anyone suspect?

The lock switch switches off all 4 window lifters. The backs don't fruntkione for that.

Headlight wipers don't do anything.

Since today, the comfort closure no longer works why.

That's a lot to start with. I'm afraid I'm going to have to get through what's connected. After a week of standing, unfortunately, the battery was also empty, is there also help?

Thank you very much for joining the group and for your help.

Greeting Christoph