Some Question that don't exist on Documentation

Hi , i have some question about Opigno i want to use score from 50 or 20 and i don't want to use Percentage but i didn't anything about this on your Documentation . and another question is that how can i set a lesson requirement for another lesson that if i don't passed this lesson then i can't go to other lesson . and last question is that Manager can set score (grade) for student or not ? because i didn't see this too . Sorry for my Questions .