although I now have a Thai license I drove on my British license here for 20 years as a resident. My insurance company even fully paid out when I had an accident. No problems with the police either they looked at the UK license and said oh you have an international license very good which of course it wasn't.
You don't get a refund if you cancel with a budget airline like this. I thought everyone knew that. Because of that there's no point in canceling. Just don't turn up.
since you qualify financially don't go and waste your money on an agent. Do it yourself. The process is very easy. If you're returning on a 30-day visa waiver go to immigration and convert your entry stamp to a non-O visa. Then go back in a couple of months after the money has seeded and get the one year retirement extension. Even though the money will have been in for 4 months you will still have to seed it from the time you apply for the non-O. But you can just relax for 2 months before getting the extension.
I have a friend who bought a beautiful ocean villa for a million dollars on a 30 year lease and he was told by the land owner he won't be able to renew it. He wants to sell the property but no one wants to buy it with only 10 years left on a non renewable lease. There will be many more cases like this.