don't register it as a business or something right now.
don't let minors in at all. not until you have extremely solid waivers written up.
in my OPINION, if you want this to really get off the ground, just draft up a very basic "you can't sue me if you get hurt here" waiver (google can probably help with this) and have a few free build-and-shoot days here and there.
take baby steps. if you invite everyone and anyone, ask them for money, and don't have any sort of waiver, you're gonna get a few rotten eggs and potential misfortunes.
keep it simple