A friend who arrived last month had his flight delayed for several hours, with the result that he arrived in Bangkok well after midnight and didn't arrive at his ASQ hotel until after 5am. They still counted his original scheduled arrival date as day zero, and his quarantine period was not extended by a day.
What will you use it for? If you plan to use it to register a marriage in Thailand (not really possible at the moment due to entry restrictions), be aware that the Thai authorities will only accept a self-serving affidavit executed at the US Embassy in Bangkok or the Consulate in Chiang Mai. They won't accept any document from the US, even if it is actually more useful in determining your marital history.
I've never asked Schwab to raise my daily limit, since it's never really been a big issue for me. The $1k limit meshes with the 30k baht ATM limit (at Krungsri, TMB, CIMB, and Citibank ATMs), so an increase would only let me make multiple pulls in one day, rather than getting more in one pull. That would be slightly more convenient than, for example, having to go to an ATM three days in a row if I need 90k baht, but that's not too big a deal for me (and the extra trips to the ATM at least get me out of the house :) ).
I've also never tried a counter withdrawal, though that seems more interesting if I could really get $3-5k at one shot with a single fee or no fee - I've just been too lazy and complacent to try, especially since my ATM fees are reimbursed anyway.
I have yet to try Transferwise, either, since - as you rightly note - it's more expensive than withdrawing from an ATM using a Schwab card. It does seem to have the advantage of being quick, and allowing moderately large transfers without having to undergo the telephone security interview that my credit union conducts every time I do a wire transfer - which is why I've only done SWIFT transfers for very large amounts (like my 800k extension deposit), where that's the best and cheapest way of getting the funds over here. Transferwise clearly has its uses, but a lot of people have been blinded by its shiny headline exchange rates - which you can never actually get, or even approach - into thinking that it's better than it really is.
I personally have never been asked for a copy of my TM-30 receipt or my lease when extending my Non-OA and then Non-O at CW, though I always brought them along just in case. I don't know whether this is somehow dependent on the circumstances of the individual applicant, or just on the whim of the officer.
That isn't correct. The rate you get at an ATM will be the Master or Visa rate, even using an ATM card - the TT rate of the bank that owns the machine never comes into the picture. I've been getting pretty much all of my baht cash from ATMs for over five years using a Schwab debit card, and can confirm that the rate I get each time is exactly what is shown on the Visa website.
That is indeed what Immigration has posted on their website, and yet the Cabinet decision and subsequent Royal Gazette announcement don't say that at all - they just say that 90 day reporting isn't required thru September 26, which is why people like the OP are confused. Given the conflict, I agree with you that the safest course is to follow the earlier date, even if it's not clear how they came up with it!
The same thing happened recently to friends of mine, and the issue really was about the Thai wife's registered address, not the American husband's. The husband wanted an extension because the wife was being treated for cancer, and the IO accepted that they were married and that they lived in their own condo in Bangkok, but she said that the extension could not be processed at CW because the address on the wife's Thai ID card was still her mother's address in Nonthaburi. To get the 60 day extension, the officer said they would either have to apply in Nonthaburi or else change the address on the ID card to Bangkok and come back to CW. She didn't care at all about the address on the TM-30.