Hello Karl,
A good question, and with recent experience of a non-Audi, is one that the supplying dealers don't seem to discuss or perhaps even understand at the salesman, initial contact level. In respect of the question about does it use Adblue then I would guess the answer is yes it does, and I would hazard a guess at the intially quanity lasting perhaps about 3,000 to 5,000 miles.
The problem we have had for many years is that the service personnel know the answers to meaningful questions we have in mind, but are isolated from the owner by the service receptionists, who may or may not know the answer. It is sometimes not easy to get the correct answer first time.
If it were mine, I would be contacting the service department and asking the questions you ask here, and getting a price for them to refill when needed. Armed with this better knowledge, I would then visit the salesman and ask the same question again and ask him to point out where the reservoir is so that you will/should know. If he doesn't know then insist he gets someone to talk to you then who does know - route to service personnel!
I believe the reservoir will be fitted with a level sensor which will warn you that it getting low, but I think you are wise to ask the questions now.
Enjoy the car.
Kind regards,
Gareth.