yes, drinks are served - two bars upstairs, one downstairs. walk around to see which once has a shorter line.
no drinks at seat, must be finished in hallway/downstairs before entering the performance hall. gotta protect the pretty carpet in there.
i'd expect that everyone in the orchestra will be standing, and that the majority of people in the side (tiered) seating will be sitting... that's generally how things go for most shows. then again people are pretty excited aboutt his show, so everyone just might be standing.
parking: there is street parking, but it might fill up eventually on a friday night with a sold-out show. get there on the early side, and i'd recommend trying west of the venue, in the side-streets around the GW campus.
FYI, Orch row B seat 121 will most probably remain empty tonight. just sayin'.