Already buying a non imm. O based on retirement in the States is the best way to go I think. First 90 days a bit of time to get a bank account which is a bit less difficult with a non imm. O visa. Walk in some braches. If you are running out of time and still have no bank account use an agent only to open a Thai bank account. (around 5,000฿ costs is reasonable). I would not do it for the year extension. You have to do this within the first 30 days, because when you want a year extension, the money must be in that bank account for 2 months before the date you ask for the year extension. Depending on the imm. office, you and y'r wife maybe need 2 seperate accounts each 800k฿ instead of 1 of 1.6mil. together. Depending visa for y'r wife is an option you have to investigate because I don't know anything about this. And maybe the non imm. O has another small advantage that you not have to prove to y'r airliner for an 'onwards ticket' should you come in on a one way ticket.
Also, when having y'r bank account, start transfering 65k฿-plus each month (12 times), so with a second year extension, you not need the 'locked' 800k฿ in the bank anymore.
And maybe a tip: if you are Dutch and have regular income like statepension (Dutch AOW) and/or other pension which exceeds 65,000฿ a month (in €), AND you have y'r Non imm. O already bought in the Netherlands, you can buy a so called 'visumondersteuningsbrief' at the Durch Embassy. Then you not need to lock up y'r 800,000฿ in the bank.
And indeed what Jan says, my extension is already 7 years 8th of january till 8th of january. It only changes e.g. should your pasport is only valid for 8 months or so.
It is 90 days later as your entry stamp. I came in 11 oktober, so could stay until 8 january. In december I made my first yearextension and got it from 8 january till 8 january following year. So nothing to do with dates on the original visa, besides you have to come in before expiring date of the visa ofcourse.
It depends how long you want to stay. If it's less than a year, the OA is nice. It's multi entry and besides the 90 day reporting, you have to do nothing. However if you want to stay longer, use a year extension, the O is better because no need of health insurance. You DO need a re-entry permit to keep the year extension alive. Ofcourse it's always good to have a health insurance but with many over here, it's tricky if they will pay.
I think I understand y'r question. If you have an onward flight, the airline and/or immigration must have a reason to refuse you. Should you NOT have an onward flight, the airlne is responsible to fly you out/back. If you have an onward flight, then the airliner is NOT responsible for y'r flight out/back. So then YOU have to pay that flight.
Brandon is right. But they want to attract more people to visit Thailand, so IF a visa kind is canceled I think it will take some time. And I don't know if it has anything to do with it, because I'm not an 'economics guy', it seems to work if I see the strength of the Thai Baht.