Just successfully got the DTV visa. Since this visa is already a multiple entry, do we still need to apply multiple entry at the airport when leave Thailand the first time with DTV?

TIA

Hi! I arrived on a TR visa and the red stamp allows me to stay until 23 May. This is my first time to do an extension, and I'd like to find out if I can get an extension for more than 30 days? Running low on passport pages so need to maximise the space I have left until I can return to Myanmar around August and hopefully receive a new passport by then.