(1)if its not busy, you could hang out for a while--but at busy times the lines (to get in) can be long, and so they would need to open up space for the waitees.
(2)In AC, I think Harrah's (now Ceasars) system and Revel will do status match.
(3)Open bar can mean lots of things: (a)self serve liquor, (b)unlimited drinks delivered by the bar tender or server. At Borgata (as far I know), it is (b), and eventually they may send you away.