no, because airport immigration just sees a valid stamp and lets you in, unless something seems shady about you.
I've been out and in 4 times with my DTV and the only thing I've been asked is "is this DTV?" And then the lady in the booth got excited and told her colleague it was her first time seeing it.
You need all of the documents you used for the visa application, but new versions with a new date.
Or you can take a weekend trip to Kuala Lumpur, Luang Prabang or another nice city nearby and come back to get a fresh 180 day stamp without needing to present any documentation.
No, it is not a requirement. But you have to input an arrival date in the application. You don't have to actually arrive on that date, it's just a legacy field from other visa type applications.
it's been literally the opposite for DTV applications. They ask for silly stuff just to ask for more and even ask you to send the same documents, that you've already sent in with your application, again.