Do they have actual seating, or do you have to mill around with a beer in your hand all night?

Some seating upstairs, standing bottom level.

If you want a seat tell them you're their for dinner at the upstairs lounge, that's the best way to get a good seat :) Or, get their early.

It depends on the show. Sometimes they set up seating on the bottom level as well.

Bottom is almost all standing room, top is bar seating with balcony overlook.

There's seating in the front too, but you can't see the stage

Depends on the show you're going to for the floor.

They have actual seating

Depends on event but upstairs it's they do