If you come visa exempt you'll be stamped in for 30 days extendable at immigration in Thailand for another 30 days. If your O-A is approved and you leave and re-enter you would be stamped in for a year. But you need to enter to get the new stamp
Brandon Thurkettle Hmm. It does say "The first application for extension of stay by the foreigner is equivalent to the notification of staying in the Kingdom over 90 days." But I have heard where they don't do it and then shake you down for not reporting. Make sure they gave you a 90 report slip. Be careful.
You can buy the right ticket to transit in BKK. Just be certain it's the right ticket. They'll sell you anything on the internet and say "self-transit". You cannot. You need to be given all boarding passes at check in.
Maybe just get a 60 day tourist visa extendable for 30 days for the first trip and further investigate the Minho at the immigration office you intend to apply at. Then do it in September.