AudiForums.com - 1986 Audi 500cs Turbo

Hey guys, this is my first time posting here. I just bought a 1986 Audi 5000cs Turbo and it has some issues. The first and most important to me is the power steering. The pump for it (I think it's at the front of the engine bay and has a belt going around it?) "bubbles" a little at the connector on the top of the pump. The guy I bought it from says he used it to commute back and forth from Livermore, CA, to San Leandro, CA every day. He said about once a month he had to refill the power steering reservoir from the Min. line back up to the Max. line. How much work is it to replace the leaky top part of the pump? Another issue is that it is a little rough idling when you have the car in a forward gear. If you've been driving, come to a complete stop, the car starts vibrating pretty hard. It's not as bad as it sounds, but it is a little annoying. The RPMs don't jump too much, maybe from about 950-1050, and as soon as you put it in Neutral it'll go up to a nice smooth 1100 or so and purrs. Maybe I should flush the tranny fluid and the final gear fluid? I want to change the fuel filter for it and in the manual it says to only use an Audi one, is this true or can I use a Fram or other name-brand filter? Sorry for cramming so many questions into one post! I love this car and I've only had it for 2 days now! It's awesome! Thanks!
-Tom

Edit: One more thing! I don't know if the original owner or the guy I bought it from ever had any of the recall work done... How long is the recall covered for and if it's still covered, where can I take this baby to get the Idle Stabilizer, Axle, Tranny Lock, Seat belts, etc, etc worked on to the full extent of the manufacturers recall? Thanks again!