Richard Clark from Immigration rules "On the filing date, the applicant must have funds deposited in a bank in Thailand of no less than Baht 800,000 for the past three months. For the first year only, the applicant must have proof of a deposit account in which said amount of funds has been maintained for no less than 60 days prior to the filing date". You can use said account, but funds can not drop below THB800,000 in that said period.
Having said that there are always exception, but in such case you have to contact a particular Embassy, like Singapore or Hong Kong. KL might be possible too.
same as Vientiane, they just look through the passport, they do not consider back to back or other time factors. They just count what is in your passport.....
never..... extension were 7 days on visa exempt, since 29 August 2014 extensions are 30days unless you are from a country which has bilateral agreement with Thailand, like Mongolia, HKG, Laos, Russia or Vietnam.