Are we allowed to use open source art/music?
Of course. The only thing that you should truly do yourself, is the programming aspect.
A bit late, but is it okay to use libraries? I know it's technically not my code, but I'm using Love2D which is pretty bare-bones.
You're free to use a library, go ahead.
He said you can use any type of library
Hi I just wanted to check my team and I are allowed to use photos and voice lines of people who are not in our team if we have their consent.
Sure, go ahead. Just as long as you do have their consent/permission.