They want all passport pages, even those that are empty. There is no way for them to know they are empty if you dont include them. They want to verify that you are still in Vietnam.
Anonymous participant if you exit Thailand, you have used up it’s one time use, so no longer a valid visa. Therefore, I think you can apply then, once you leave.
Is your current visa a single entry or multi entry tourist visa? You can’t apply until that visa expires. If single entry, it is expired/finished when you exit Thailand to go somewhere and apply for the DTV. However, if multiple entry, you will need to wait until the expiration date on the visa. You would still need to exit the county to apply..
to double check your understanding, if you enter before the expiration date, you get 60 days, not 6 months. After that, you wouldn’t be able to use again, because you can only use it to enter before expiration date
The Thai Ministry or Foreign Affairs issued today a travel advisory for all Thai nationals. They should only travel to Thailand if absolutely necessary. This may mean that the embassy has a reduction in staff and/or consular services (who also issue visas) might be focusing more on affairs related to Thai nationals in Cambodia.