You can direct deposit or direct transfer to your Thai bank cheaply - price depends on the bank. K bank is recommended. I use my credit unions debit card at the Bangkok bank exchange window for free. Limit is 200,000B per time.
doesn't matter. O-A on US means you need insurance. O-A in Thailand means no insurance. Show 65,000 each month deposits or 800,000 in bank. Does not include covid insurance.