Prize money is something that is totally up to the organizer, which would be you.
In the NorthEast, many organizers try to give back all entry fees to the prize pool, if at all possible. If you have sponsors, even betterer.
BE aware of your football stadium... find out what the stadium people expect as far as wear and tear on their field.
Then, I would be very vocal, even putting it in your cook's packet, about what you expect from teams as far as clean up goes. I know of some events that have taken a clean-up deposit, $50 or so per team, and not returned it until they have 'checked you out'. There ARE going to be scorched areas in the grass, along with MAJOR tamping down of it as well, due to foot traffic - within teams sites.
One other thing, there were some issues at another event that was held in an oval, with teams getting in and out if the outer sites were already full up.
GET AS MANY VOLUNTEERS AS YOU CAN TO HELP YOU AND PRACTICE DELEGATING!
Babyboomerboy, I would be happy to help you with anything I can, my husband and I run a small-ish event and I like to think I have an organizer's perspective, as well as a cook's and a KCBS CBJ's. If you take your time, find out as much as you can, and basically attempt to do right by everyone, teams and judges will come. There are going to be speedbumps, and everyone expects them at a first year event.
Regardless... listen and learn from others, be available, and communicate to everyone involved and it will be successful...
Feel free to PM me anytime...