what does it save? You get 60 days both ways and have to extend for 30 days. Done it numerous times in UK online, 90 days gives you 60 and still have to extend for 30 days in Thailand. Less than 40 minutes in immigration, not a big issue.
Nobody knows, it's new. Nobody has extended for the first time yet, who knows what's needed to extend.... Not even immigration knows yet what's needed to extend.
Opened account myself at BKK bank 2nd Road Jomtien 300 yards from immigration. Was on 60 day tourist visa. Ask what they need go away get all and return. Wasn't too difficult.