The new online system gives a pdf download so that can be kept and reprinted ...I always take an additional screenshot and file as a backup ...I have been known to delete things haha
You got a visa exempt entry and then a 30 day extension. Only 1 extension is allowed. You will now have to do a border bounce or visa run outside of thailand and re enter
Suvarnabhumi (departure exit 2 post security, before immigration exit) is so easy its not worth a visit to an io unless youre there for another reason ...