The eastern leg sucks! No representing for the southeast?
I'm hoping they plan to expand that up a good bit.
In answer to the OP, I don't think I've ever been to a signing or author meet-n-greet where you were required to do anything but show up and be nice. Bring or buy the books you want signed, ask a question if you got one, don't be a time-burglar. It's polite if you buy a book while you're there, but I don't think it's ever been mandatory, just good manners.
Last one I went to was with Carl Hiassen, where he did a speech and took questions and I got to ask if he felt pressure or had difficulty with a need to continually one-up the craziness of his villains, given that some of them are fairly batshit-crazy, to which he replied that after you've written a character with a weedwhacker attached to the stump of one arm and the decaying severed head of a pit bull with it's teeth buried to the bone in the other, you pretty much stop trying to keep score.