So far the forecast doesn't say rain for Friday, or any day Labor Day weekend, so we may be fine in the square. You're right, the mall probably wouldn't like us bringing in lots of food, but they might grudgingly allow us to stay if we buy some foodcourt food. We'll just have to see what happens if it comes to that.
As far as how much food to bring, it depends on how okay you are with having leftovers. If you bring enough for everyone, it probably won't all get eaten since there will be other food and not everyone will want some of everything. So if you don't want leftovers, don't bring too much. I personally will bring a lot of potato pancakes because I know I'll gladly eat the leftovers for the rest of the week. :9