Strange that the airline asked, typically that's immigrations job. Can't you show a bank account app with the cash in it? 10K baht is pocket change, you really don't have it handy?
In all likeliness you'll be given an under consideration stamp for a period of time, possibly 30 days. If you bought a reentry permit after you've been given that stamp then you would have to return by the date on the under consideration stamp to get your full year inked in.
Yeah they are a bit shady there at Nong Khai. The lady who takes your money, passport, and hands you the arrival card. USD notes are cheaper, buy them in baht on the north side of that same building, very very fair exchange rate.
Excuse me. You're deadass wrong. There are 2 tourist class visas, 3 if you count the DTV, 4 if you count VOA. You'll find most all of them on the Thai evisa website under the classification tourist visa. A Non Imm class visa, especially an OA (retirement/age 50+) is not a tourist visa classification, it's a long stay visa with yearly extensions. Stop with your fairy tale.
I've included pictures, sorry, ran out of crayons.