On the lotto: I prefer having a set number for the win, because all the points spent in GCeA will add up so quickly it will make the person who wins it mind-numbingly rich if they win. The second or third options sound best to me.

On the quests: I know they probably won't go to the pre-mades first unless they have writers block or it's too early for their own quest to make sense. However, just in case, I'd have at least one or two pre-mades. Also, by making pre-mades, you could make the opportunity to have people play as other characters important to GCeA's backstory. (though, they could also do this with the custom-made ones-as in, the ones they make with you.)

Also, when I said "How about just giving them a set amount of 'points' that you have to spend during the event, with no way to restock them?," I meant "No way to get additional points, period, not even through posting." Just clarifying a possibly easy to misunderstand point.

If there is THAT much stuff to be won in a quest, that's fine. I'd make sure they get a majority, or at least half, of the stuff they won over, especially if they won. As these are possibly non canon, 'winning' the sidequests and getting the 'happy' ending isn't exactly a must...