Depends on the embassy/consulate...each place/country has its own rules. For some a month is enough, others ask for 3 or 6 months, and there are places where they just want to see the money in the account...even same day transfer is accepted.
Nope, multiple entry means "unlimited entries are granted within the validity". So... DTV is a visa with an "integrated multiple (re-)entry permit)", if you want to call it that way... :-)
"4. Financial evidence: amount of no less than 500,000 THB OR equivalent amount in foreign currency e.g. bank statements OR sponsorship letter covering living expenses."