I'm going to the Thursday night event with my kids, but DH (who has the costume) won't be there as he has tickets for Wootstock which is unfortunately the same night.
My understanding is that all of the main actors from the film have showed up at one of these events before... except NPH. For some reason he has never shown up to one.
It also occurred to me that Simon Helberg will also possibly be around 'the area' on Thursday night, as he's doing the BBT panel on Friday. You never know if he might show too...
ETA If you want a Captain Hammer shirt, you can probably get one at the Con. I'm pretty sure the t-shirt booth would sell them.