What are the steps to obtain a retirement visa in Thailand for someone over 50, and can a dependent minor follow on that visa?

Hello. I would like to ask a question (well 2 questions) that is specific to me. Sadly I am still confused. I am from the USA and came here on 45 day visa exempt Phuket sandbox program. I went and got the 60 day Covid extension and will go back November 1 to get my passport stamped (not really sure, they gave me a blue piece of paper and said to come back November 1st). I also filled out some paperwork with the apartment I am staying in and turned that into the immigration office. They accepted and said ok.

My 1st question: I would like to get a retirement visa. I am over 50 and have the 800,000 baht in a bank and it has been there for over 3 months. What do I need to do first and how long does it take?

My 2nd question: I have my 16 year old son with me. He did the Covid extension too. Can he follow on my retirement visa?

Thank you.