While you can have 15A receptacles on a 20A circuit, you CANNOT put a 20A receptacle on a 15A circuit. Whether you can swap the circuit breaker to 20A would be determined by the wire gauge size. It must be at least 12g wire to swap it to a 20A CB. It's probably 14g. Can't help you with brands. Not all GFCI have a load output, so some cannot be used to protect those downstream.