I suggest you schedule consultations with a California family law attorney and with an Arizona family law attorney so that you can compare. You may be able to get free consultations on the phone. If not, just pay for an hour of each attorney's time. You want to get started on the right foot, especially since your kids are involved.
Here's a link to a blog article another attorney in my office wrote as a child custody primer. Hope this helps get you started:
Dianne is right about that - anyone can file the paperwork.
Just so you know, the Plaintiff in a divorce case in California is referred to as the Petitioner. The other party is referred to as the Respondent.
Best of luck.
I agree with David. You should pay for a consultation with an attorney in your area - just to get the forms straight. Here's a blog article I wrote on the paperwork process, but it's probably not as detailed as you're going to need:
I agree with John. This may end up being quite simple for you. Because you were together for such a short time, you may qualify for a Summary Dissolution. Below are links to several articles that may be useful for you. Good luck and I hope these help:
I agree with Martha's response. It sounds like you are fairly well educated on the topic, but we have a brief explanation of the differences between legal and physical custody in California on our website. Here's a link for your convenience: