okay i go out to check out the audi a4, and on the back it says audi s4, and it says quattro in the dash. what does this mean? is it a audi a4 or s4? is it a better car.

some things that's wrong with it

1. flex pipe is done.

2. doesn't seems like the turbo gets spool( maybe cuz of flex pipe leak)

3. leaks power steering fluid

4. driver side window doesn't work.

5 brakes feel soapy.

the seller didn't seem to take good care of it should i buy it and fix all of these things if i can get the car for cheap?