I had a friend leave last year and he was at the airport when I told him it's just been announced its been extended. If there was more notice people could plan better.
weeks left on your current visa. Some immigration offices tell you to come back a few days nearer the expiry date. This isn't the first time the covid extension has been extended at the last hour.
Yes you need a residency letter from immigration. It costs 300b. So when you apply for one you need to take 2 passport photos with you and proof where you are living. I've had BKK bank account 18 months and had to do the same.