I understand that the 300 baht will go into a slush fund that will be used to support hotels and other tourist reliant businesses should there be another wave of COVID infections.
I use Transfer every two weeks. I think it depends on what arrangement you have with your sending and receiving bank. I think the most I’ve ever waited is about five hours. But that’s the exception. Most transaction I make are completed in seconds or at most, a few minutes or an hour or two.
immigration offices have a reasonable amount of latitude when it comes to the documentation they require. Here in Samui to get a 12 month extension of stay based on a Non OA for example, you must provide a medical certificate, a satellite photo of where you live as well as a hand drawn map. This is in addition to all the other usual stuff.