Can a psychiatric nurse practitioner prescribe meds?

Yes, absolutely. As long as they are board certified and you will need a DEA for psych practice.

The short answer is yes, I prescribe psych meds. The level of autonomy to do so varies from state to state but in CA I can with a physician overseeing my charts.

Yes, same rules as any other prescribing NP in your state

Yes, if the nurse is a registered nurse with the council certificated