Welcome! I strongly suggest you grab a tasty beverage and head on over to TDIclub.com. Read the FAQ, read the stickies and How To's, and browse the entire forum. Oodles and oodles of the info you need to take care of your car right.
First things first, get the timing belt (and water pump, tensioner, three rollers, stretch bolts) done...NOW! Even if the seller claims it was done...DON'T TAKE A CHANCE. Get it done by a competent TDI mechanic. NOT a VW DEALER, not some generic chain shop, not an independent shop that has never seen a TDI before...much less a VW. There are numerous TDI mechanics all across the country who have the special tools (there are numerous specialty tools required) and know-how to do it right. You can't change the TB just like any old gasser. You can find a good mechanic near you on TDIclub...or just tell me where you are located and I will point you in the right direction.
If you ever have any question you can't find the answer to, or u just aren't sure, drop me a line and I will set you straight or point you in the right direction. These are great cars when maintained correctly, they can last 500k miles or more.
welcome from another Texas tdi owner.DZLBUG gave some good advice.Don't know where you are located but there are some good tdi guru's in Texas.If nothing else you should have one of them check the car out for you,there are a lot of quirks with these cars.Check out TDIclub.com and enjoy your new (to you) car.