K.B, could you edit your post to make yours questions 7 and 8? That way people can add questions to the list.
Bandy:
2&3) That's always been up to the vendor. Some are just unloading, others have wants of their own. The only thing you can't do is sell items unless you are a vendor. But, if you have something some guy wants, and a vendor has something you want, you can ask that guy to buy it for you in exchange for your item. As long as the only people receiving money for goods are the vendors, it's okay.
4) Groups of people tend to end up in different spots after the meet. It's up to you to make plans during the day. Odds are you'll find someone that would be interested in joining you, so it's a good idea to keep some money aside for eats.
5) Last year there were sign ups. It's safe to assume there will be again.
6) Because this is a Joe-specific event, there are almost as many bins as there are collectors. You probably won't have to worry about lines for specific items. However, there is the free table, and everyone should have a fair shot at it.