I'm probably not the right guy to answer this but . . . . some thoughts. Most of the kiters are pretty self sufficient. Once we get pointed to the right field, we'll get our stuff set up & ready to go. So the volunteers are more needed for setting up and cleaning up the festival fields (i.e. putting up stakes & tape to fence off the demo/show kite fields), and for directing traffic (bigger festivals), helping attendees answering questions. You also should plan on someone to empty trash bins, especially near the food vendors. Given that it's your first year, you probably don't need as much support as you might later on assuming the event grows. Also, some festivals have volunteers to help with kid's kite making and other crafts/activities.
That said . . . at well run festivals, there may be a lot more volunteers that we don't see . . . . because we're too busy flying. I think there's one four day fest we went to last year that had hundreds of volunteers (but it's a very big festival with music, art, a whole "vendor row" and lots going on besides just kites).
I think someone else should chime in, because I've never organized a festival . . . and I'm guessing I get to have so much fun flying because there are more volunteers doing more stuff than I realize!