First off let me say congratulations for working with the youth promoting archery. I think the team shoot you spoke of with 1 youth and 1 adult is great. I wish we could get enough youngens at our range to do something like that.
I think the money shoot would go over just fine. Picking the right date is the hardest part. I wouldn't think the $50 entry would detour to many. We spend way more that that to go to a ASA, (motels, food, gas, entry fees,) usually totaling around $500 for me in the amateur senior class. And if I win
1st place (not likely) I don't win enough to break even. ????????
I think if you are only going to have 1 class then the speed limit would help to even the field for the ladies, youth and us old timers (seniors). I see nothing wrong with the 280 speed limit. Granted most bows these days shoot way over that, it is much easier to slow one down than for a short draw archer trying to get every fps they can out of one. With 3D archery aging the way it is, the senior classes seems to be one of the bigger growing classes any more.
Definitely bust groups!!!! Even better would be have a shotgun start and randomly assign shooters to targets. I vote for the low 12's too.
I'm not for sure letting the professional and semi professional shooters in would help your participation. Maybe it would, maybe not.