I know most airlines will not let you fly without 6 months remaining but you CAN enter Thailand with less than 6 months on your passport, fact, you just cannot be stamped in beyond your passport expiry, obviously. If RTE Delhi will not issue a visa with less than 6 months remaining that is totally different to obtaining an entry stamp at Immigration. ;)
No it is not, it is a type of tourist visa and I expect people who try to live in Thailand on a DTV will see increasing difficulty as their number of days stay starts to add up