Since you already have the car, I would suggest for you to work on the most important/drivability issues.
I would replace those valve cover gaskets quickly. There is a recall bulletin for the front one... prolly can get it replaced free from a GM dealer. Get your VIN number and call a local GM dealer and ask if the recall service has been completed or not. But these cars are known for catching on fire... so I think thats the first thing to address.
I would change the oil, tranny fluid & filter, and coolant. Check belts and hoses for cracks ..etc. The ABS/TCS issue is most likey the sensors in the front wheels behind the rotors. It would be a good idea to get the car scanned for Check Engine codes as well. Once you have those you can come here and see what the issue is.
You got the car now, lets make it better. Also, check out the HOW TO section on the forum. Lots of good info there.
