Anonymous participant 966 they might be the only one being so aggressive with KYC at the moment. But no other bank will open an account for tourists, and others will limit your account or close it if they find out too.
I'm not sure if you've been hiding under a rock or something, but this is not a new issue.
Banks in Thailand no longer support bank accounts for tourists. You are a tourist with a tourist visa. Your bank is checking up on its existing customers to see if they meet the current qualifications, which you do not. They are a private entity and have the ability to deny service to anyone they like.
2) completely depends on the Krabi immigration policy. Many offices don't even require a lease as part of the extension paperwork. But each immigration office sets their own policies. For 1-year extensions it's always best to go to the immigration ahead of time and ask them for their handout of requirements, as sometimes they even change from year to year.
But METV is a TOURIST visa. That means it's for tourists. Whether you have a visa or not, immigration is the one who decides if you get to enter Thailand. And if you just spent a potential 9 months in Thailand and try to return as a tourist 3 months later, they're likely to take a dim view.