I agree with Paul and Baz. We drove down to Samui a few months ago for a vacation and must admit a couple of weeks is long enough. I think Phuket has more to offer, if it is island life you want and you don't need to catch the ferry to explore other places. We live in Hua Hin and the beaches are not as nice, but it's a great location to go south to the islands or north to Bangkok if you get a car. Try a few places before you settle down.
I love Cyprus, but think Thailand is a wonderful place to retire. Good luck.
He can get a non O visa based on retirement inside Thailand if he meets the requirements. He needs to open a bank account in Thailand first and this is virtually impossible without a long term visa these days.
Ask the agency to open a bank account for him. The rest he can do himself at immigration.
The easiest way is to apply for a non O Visa based on retirement online from the Thai Embassy in your country, before coming to Thailand. This visa enables you to open a bank account when you get to Thailand and then deposit 800,000 Baht, to be able to extend your stay for 12 months.
It is virtually impossible to open a bank account inside Thailand without a long term visa these days, and I understand anecdotally even more so for USA citizens.
I would be wary about transferring the funds personally as if anything goes wrong you are starting from the beginning, but that's not to say it can't be done.
If you wait 3 months and transfer 400k first to your new account wait until it shows in your new account then transfer the other 400k, I think that is the safest method.
I keep a copy of the information my bank issued to me, so that if they don't know what I require, I get the photocopy out and show them. This has worked so far (that could change, I realise).