As for his way of calculating grades, as long as he is consistent, there is no problem for him. If not. he will be in trouble. He could possibly sued for race discrimination for one example. also, can sue him for other various compensation, depending on your lawyer.
If there no syllabi passed out, there no way he can prove he had "attendance and performance" criteria for calculating grades.
I think you can and will win. Best of the luck to ya.