Depending on the free at your bank, swift is usually cheaper than wise for larger amounts (more than 200k). Transfer in your native currency, Thai rate for your native currency will be better than your bank rates for Bhat.
The goal of that banked money is to be a reserve for expenses (medical, emergency travel, family emergency). If the banks block the funds, what's the point of having it at all. Get hit by a bus and can't pay the medical expenses because the bank has a hold on your funds?
Passport, tm-30, passport photo. Residency certificate are type specific so your need separate ones for banking, drivers license(s), vehicle purchase/transfer/registration. RC's are valid for 30 days. I take along my lease agreement too.
Depends on your country and their DTA with Thailand. Depends on the source of the money. Depends on if you've been in Thailand for more than 180 days in a calendar year. So the answer is "it depends". Giving more complete info will get a more definitive answer.