Here is for a 2001 and 2004 1.8T.
According to Bentley and probably many others, it is recommended to inspect the timing belt and tensioner every 20k and replace it every 60k. A timing belt will never just let go without any signs of wear so if you are concerned about your belt, just give it a good inspection and check for cracks, splitting, fraying, pieces of belt around the shroud etc.
As for the oil, you will hear 148,394 different opinions. The general consensus is probably to change it between 3-5k miles. VW recommends an oil that meets the 502.00, 501.01, or 500.00 rating. VW prefers 5W-40 or 10W-40.