Legal Question in Criminal Law in California

1. Sky's the limit. Could be charged as aggravated battery, mayhem or attempted murder.

2. Yes.

Your question seems to presume that both parties in a fist fight are equally culpable. Sometimes that's true, but sometimes it isn't. If one of the participants clearly started the fight and the other merely used a reasonable amount of force to protect himself, then only the aggressor has committed a crime. But if the other person responds with an unreasonable amount of force and injures or kills the aggressor, then he is also guilty of a crime.