Depends on alot of thing. Many Champions can make several hundred thousand a fight (not including win bonuses, normal wage, other bonuses, etc.), while other fighters (particularly those not signed) can make only a couple of thousand.
It depends on the popularity of the fighter and how well she does in a fight. They get win bonuses and all sorts of other bonuses. So it varies between each of them; it also depends on how big the...
Not much. Some Winner-take-all tournaments award fighter up to 10,000 dollars but most amateur fighters get money buy selling tickets to their own fights.