looking to buy an s4 but i have some questions?

[grncivicdhr]

Ok. i'm looking at 93-94 audi s4's and i have a few questions.

1)what are the different chassis designations for S4s. i have a 92 240sx right now. so its an s13 model (94-98 is s14)
2)most cars i've seen have anywhere from 120k to 190k miles on them. what should i be looking for on these older cars?

i'm very interested in this car. i think the styling is excellent (i've never seen a car look nicer on a set of BBS's) and i'd like to move on this within the next two months. any help would be great or any car specific web site would be cool too.