Ok, well, let's go in order.
1) Chanting/Magic is okay. While 'real' magic doesn't exist, you could, say, pass it off as something like "My character likes to do it because it's thematic" or "My character chants spells because it helps him/her concentrate and use their power".
2) A minotaur-like creature would be fine, as some powers do cause physical mutations.
3) I don't see anything wrong with that. I guess they'd classify as whatever they use the most. If they're mostly using tech, they'd be Class A.