Legal Question in Family Law in California

Your rights as a person representing them self is the same as an attorney who might represent you, with the exception that as to service of any documents or legal papers you are treated as being the client and some one else must make the service.

Yes, but the subpoena must be obtained from the court.

Depends upon whether you are in state or federal court. Ask the clerk of the particular court you are in. Some places the clerks want to see and issue each one after you have it filled in; other courts will hand you pre-signed and stamped but otherwise blank subpoena forms.