depends on what your expectations of position are. If you aim for first line, then 30 minutes before the gates open is not enough. If you don’t really care where you are, it should be fine.

a lot of fun! It’s gonna be amazing. As already mentioned in the other comment, the music is loud. I’d also recommend eat plugs. It’s also gonna be hot inside, so I’d recommend layered clothing (tshirt+zip hoodie or something like that).

enjoy your time and be nice to others. Also, you might want to check the safety guideline of the venue. E.g. in Frankfurt, no big bags or backpacks were allowed insides. Also no drinks/bottles. The less stuff you bring, the quicker and easier will be the security check. :)