Mannnn I had an '04 Audi that I loved. The fuel pump went out at 49,898 miles and the warranty was up at 50k. LUCKY.
I traded it in. A year and a half later I got a recall for the fuel pump, lol.
Anyhow it sounds like you have quite the combination of things going on. Start with the codes and lets get to work! O2 sensors are generally not hard to remove, however... depending on how old the car is they could be IN there...
ABS light... oil pressure light... Sounds like you need the 50 cent upgrade.