Hi Vii!
1. Yes, the set up will be like Global Game Jam. We will have an hour or two as introduction and idea pitching/group formations. Food will also be provided and the location is in Weston as well. For people that can't attend in person or don't go to NJIT, they can also just upload a game onto the page during the event hours.
2. Head starts are fine. In fact, having a concept/design document/presentation prepared is encouraged! Since there are many additional challenges/diversifiers that I recommend people to try to tackle (at least 2 or 3, or all of them if they really want to). The only rule is that they can't come in with a game that already exists/is halfway finished, because the goal is to jam and let everyone have a chance to express their creativity and ideas.