First, welcome to the forum.
To answer your first question:
People dress differently for the banquet. Some go with casual dress--last year I wore kakhi's with a collared shirt and some nicer shoes. Some wear a button up shirt and a tie, with slacks and dress shoes, and still others go the entire suit and tie route. So, basically, anything from casual dress up is pretty much good, if you want to dress up. As for the rest of the fest, I just wore whatever I felt like--shorts and a t-shirt, etc. Pack a light jacket, because even though we're in a heat wave this summer, last year I found myself getting chilly a few times throughout the weekend.
And to answer your second one, I"m not sure how common it is for cast and crew to just show up. I mean, anyone is welcome, and they may be adding people to the guest list of stars all the way up to the week of the actual fest, so I'd just keep an eye out on the ShadowGram email updates, and if you don't hear anything at all, then look around for Denise at the fest, and, if you find her, get some alone time with her to talk!
Hope this helps. See ya there!
