Can't help on everything I am afraid but from experience of owning a TT180 for 3 years:

You don't necessarily need the upgraded alloys. It's easy to get them on ebay afterwards depending on what you want of course. I wanted to go from 16's to 17's and so many people were fitting the later 18's the choice of second hand 17's was huge.

If a car has been properly looked after 61k is nothing these days. Depends how much of the service history and ownership history you have. We had a 2001 model and took it from 42k to 50k.

How many miles do you do? Running costs of our TT were very low because it was my partners run around. Biggest issue we had was having to replace the quattro haldex drive control unit. £960 fortunately the supplying non franchised dealer paid for it!