Usually when I go to my SCB branch at Central Festival and tell them I need the bank statement for my visa extension they already know what I mean and print exactly what I need. I don't know if it's the same with BKK bank though. (I peeked on the bank employee screen and they have like a folder with both the statement and letter of income for immigration purposes ready to print... )
90 day reports are very easy in Chiang Mai and take 5 minutes. Just follow the indications for the drive in and give your passport to the officer at the window.