Legal Question in Landlord & Tenant Law in California

There is no set amount. You have to look at what the duties are , how long they will take, level of prior experience, etc. If you are in a rent control city then you want the manager to pay rent and you then pay him as an independent contractor so that if you late rent out his apartment you do not have problem that he was paying below market rent.

This is not a legal issue. There is no law on the subject, only about how much credit you can take for rent for the manager's apartment.