The questions were more meant to make you look at the outline of the project tiers more than obtain an actual answer What if someone shows up with the entire first grade of a elementary school, say 200 6yr olds? It was just a suggestion that you might want to spell out how many is in a group for $500 and what ages the groups are appropriate for.

As for the block interface, its a good idea. Lego used it with their first Mindstorm computer (maybe later ones too, dunno, only ever owned the first one) and it seemed to work very well. Its an easy representation of logic steps and kids old enough to play Minecraft and create some of the redstone devices they do out of very basic components surely could grasp the block nature of coding as well. And this concept leads into flow-charting and OOP in higher languages so its not a loss.

Oh, and congrats on making your first goal! Looks you are in striking distance of the $4k. Get out there and drum up the support!