unless the US embassy can validate your 65,000฿ monthly income, that cannot be used in the first year. But during the 1st year, you can deposit 65,000฿ into your account every month, then that method can be used for you 2nd 1 year extension
Spend your 2 weeks looking at areas where you might like to live and make contact with a few estate agents. There's no point applying for a Non-O at this stage if you are planning to leave Thailand for a few months again. When you know when you are ready to move here, apply online for your Non-O visa from your home country. This gets you stamped in for your initial 90 days. To get a bank account opened, you will need to have a residence certificate, your passport, a photographic home ID. Once you bank account is opened, you need to deposit 800,000฿ into that account 2 months prior to you needing you 1 year extension. And that needs ti saty there for 3 months after you get your extension, but not drop below 400,000฿ for the remaining 7 months when it needs to be back to 800,000฿ 2 months before you apply for your 2nd 1 year extension.
You won't necessarily even need an exit flight. It'll be down to whichever airline you use. I came in on Thai Airways from Heathrow on a oneway ticket visa exemption. No questions, no issues