Your shows for 18+ yrs, I have heard that "kids" under age can come with a "parent". Does it have to be an actual parent or could I (over the age of 25) bring my brother (age 16)?

Must be the real parent/guardian if under.

Not sure but you should call them first.

I have seen young kids at shows, but I assume that they just need a legal age guardian. Anyone uner 21 is not allowed to leave the venue for any reason, or they wont be let back in. For sure I would call the venue before hand to workout any details, instead of risking being turned away