Lao (Vientiane, Savannakhet) and Burma (Yangon) are still walk-in, but you need to make an appointment first. Without appointment you can do it in Indonesia (Jakarta), Taiwan (Taipei) and Philippines (Manila). Hanoi takes about 5 working days (not included the day you apply).
Jakarta seems to be pretty easy, Laos is the cheapest with exactly 10k (in Baht).
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... :-)