If it goes below 400k during the time between visa extensions you will have to explain it to immigration. They may deny the extension and make you apply all over again.

Whenever the kids are out of school prices will double or triple

Get the passport replaced. You have too many stamps for them to criticize you on.

Don't extend, you don't have time to deal with the visa struggle. just fly out to Malaysia after 30 days and come back after a week in Malaysia.

Come to Pattaya with a carry on bag each and visit a few visa agents and get some pricing info. Make sure you can last a few months on a tourist visa with out getting bored

When it's published in the royal gazette then it's real and approved

Each office interprets the rules in a way that works best for them, puts the interpretion on a piece of paper, and shows to foreigners. Each offices paper is different.

No matter which long term visa your on, you will always be treated as a tourist, and as such why would they want to tax you? It would only cause you to flee to another country and stop spending all your retirement money in Thailand

Google "onward ticket" to understand

All of my banks won't send 2FA messages via Google voice. The thing that worked best for me so far is 2 phones one with mint ($15 a month) or tello ($10 a month) that go over T-Mobile network in us, and allow wifi dialing for voice and txt messages while overseas. Put the US phone in airplane mode, turn on wifi and let the phone with the Thai sim run a WiFi hotspot for ya.