I don't know how much my tidbits of info will help, but I did a $24,000+ fundraiser for my kid's school in February.
We didn't do any demo at all, we set up all of my products for people to see it, touch it, feel it before we started our fundraiser. I think if you are doing demo stations I would keep it to 2 hours at the longest, probably more like 1 or 1-1/2. I would maybe give some sort of bigger prize for coming to the kick off. I gave each kid 2 catalogs and they also had two weeks to sell products. I gave a $100 gift certificate to the top sales. My best bits of advice...
Stay VERY organized! If you get unorganized you may never regain control again.
Give each person a goal to reach. I think that makes a huge difference.
Give very good instructions on how to total order and such.
Allow some extra time when you close your show and when your orders come in. It took us 4+ days to sort and bag everything.
Let me know if I can be of any additional help!