The inmate determines who they want on their call list, and unless there is something within the offender's file that would obviate a candidate, anyone can be a visitor. Unless the visitor is a felon, then it would require permission from the warden.

https://www.inmateaid.com/shop/magazines/category/ethnic-espanol/19

As often as they want, as long as there is money on their books to make the calls

Your inmate gets the approval notices from their counselor and will have to let you know either by phone or a letter - the institution does not notify people whatsoever.

The entire visitation process for the Arizona State Prison Complex (including ASPC Yuma - La Paz Unit) is online: https://www.inmateaid.com/visitation/aspc-yuma-la-paz-unit

Parole violation with possession will probably cause that offender to go back and finish their original sentence with no chance for any good time. The other charges for drugs will probably not add additional time.

The old charges are the problem. The judge will look at priors and that this offender apparently doesn't take the protection order seriously. He could sit for a while with no bail before they even determine what they are looking to offer him. Please remember we are just guessing from the limited information in the question above.

you can call the prison and ask to speak to the mail room

The postcard will get there in a day or two (the mail room staff decides when they will actually hand it out at mail call). The calls are different in every prison/jail. Where is he incarcerated? We will give you an honest estimate if we can help save you money, or not.

Juvenile offenders are not allowed to call anyone but their immediate family, girlfriends are not on that list.