I love how berserker is straight up Guts XD

I am working on my CS, but there are some questions if I may:

1. Magic circuit quality / quantity: how do I define these? Are there some balance system in place?
   I believe this should have some justifications in my character's bio, yes?
2. Do my character have to be a magi? Or is the church / accidental bystander that somehow got involved allowed as well?

Thank you :)