More and more people are receiving it. It's on process. Thailand has joined the CRS. If you have registered your account on a working visa, it may not be required anymore.
It doesn’t matter what visa you have or which branch. It applies now to most banks (I’ve seen this at TTB, Kasikorn, Bangkok Bank, Krungsri, Krungthai), and all of them will definitely request it. If you’re a foreigner holding a Thai bank account, you’ll be required to provide a TIN or a valid reason for not having one; the visa doesn't change anything.
I’m not sure how that works, but I wouldn’t risk using a random number. Thailand is part of the CRS, and banks have the right to close an account if they detect fraud.
Yes, most and very soon all bank account holders will need to provide a valid tax number in order to keep the account open and if not possible, will need to provide a valid reason.