Is there a specific area where fans are allowed to wait for the artists after the the show (in case the artists want to sign autographs, etc... kind of a stage-door area)?

I'm not sure about that, stuff like that still happens after concerts? Someone has to know someone...

Probably depends on the artist, if they want to sign or not. After the concert there is a rush to usher everyone out to parking/pick up

Not that I noticed, it seemed everyone was more interested in getting to the pick up areas to get taken back to the off site parking lots