There is a red carpet thing just outside the front door and along 44th (?) street, which a bunch of photographers and press and a few fans, but nothing huge.
I don't remember how long the show was in 2012 when I went, maybe along the lines of 2h?
The theater would be open at least a half hour before I think, but I don't know for sure because I was watching the red carpet and didn't go in until 5 minutes or so to 8.
There is no dress code or anything.
Hope that helps!