after switching to 65k method yes your 800k is set free.....i use only one acct for immigration....if you are planning to use 2 accts then u will need to show both accts to immigration
90days report is free(unless agent) do in person if first time or you left the country and came back subsequently can do online....saw many agents doing reports for their clients during my last visit (was wondering why so many thais at the 90days report counter)
Atm charges 220baht for using any foreign cards and the 350baht may be the fees Wise charges for over the free withdrawal limit....it's better to withdraw with a foreign credit/debit card then the wise debit card but u do lose out on exchange rate...
I did that at bkk branch (CW immigration bkk) after paying 100baht for the letter and 100baht for the stamped and signed statement before going upstairs for immigration