There's no such thing as a 60 day visa on arrival. Visa on arrival is for a small group of countries who must apply for and pay for a visa at the airport.
If you have a UK passport then you qualify for visa exempt (not any visa. It means you are exempt from needing a visa) and will receive 60 days permission to stay. You can apply one time for a 30 day extension. Most immigration offices will accept an application for extension when you have 30 days or less left on your entry stamp. You'll receive the extension immediately when you apply, you don't have to go back for it.
Attached is a list of common requirements, but each immigration office sets their own requirements so it may not be the same.
No, no one can tell you. They just switched to e-visa on the 8th and have only been accepting online applications for less than a week. Anyone who has any experience from the past is irrelevant.
you can do it in whatever order you want, but you can't use your visa again once the expiration date has passed. That's why you leave and re-enter Thailand the day before it expires.
1) The visa gives you permission to stay for 180 days each time you enter. After that you can do a border bounce for a new 180 day stamp or you can apply one time each entry for a 180 day extension. No one knows what the extension entails, how much it will cost, or any other details yet as we are still months away from the first person being able to apply and the immigration offices don't even know anything yet.
2) CAN he partake in courses? It's one of the requirements for a category of DTV. Taking classes has no visa requirement in Thailand. Anyone can take classes regardless of what visa they have.
3) You need to check with the embassy. Each embassy sets their own requirements, and some will require a dependent to show their own proof of funds and some will not.