The school may work you 12 hours a day (10 teaching hours with 2 hours of breaks) but that will only be on saturday and the normal workload for most teachers here is 8 hours. Then perhaps you will work 6 hours on Sunday and you have the rest of the week free. The pay is 80 / hour and yes, like in most schools, your visa will be cancelled if you leave the school before you finish your contract. Cant say much about the headmaster except I have had no problems with him personally, but you are not the first person to say something like this about him. The school does have its problems but none like what you mentioned, atleast in my experience here.