-the monthly insurance be?
-the monthly car payment be?

Really depends buddy.
For monthly payments-
What year Audi?
Is it an A8L or just An A8?
What kind of Interior or options are in the car?
Motor size?
DVD Nav?
for Insurance-
Garaged?
Multi car discount?
Kind of security system in car?
House insured with same people?
Driving record?
The question you asked is way to broad answer some of these and re-post.