All my banks refuse to send 2fa codes to app based VOIP numbers like Google voice, WhatsApp, etc. If you do porr you number over to a VOIP app the banks will detect the transfer after 30 days and the cut off the 2fa codes to the number. Your best bet on phones that work in Asia and the US is to get 2 Samsung A15 phones at bestbuy (they sell them unlocked) and make one the hotspot for the other. Transfer your number to tello, as you can change the plan each month and just just pay $7 a month when your in Asia, and go unlimited for $25 a month in america.
As long as your bio page has no rips or smudges, your good to go. Girlfriend washed min and the stamps were all over the place some missing, some went through to the other page. As soon as you put your fingers on the scanner at border control on the way out, your visa info will pop up on the screen for the immigration officer
1 month, 2 months, 3 months doesn't matter. They want you to come back to Thailand and spend money after your class for the next 5 years without having to worry about vusas