They won't ask you for an interview in Vietnam. At a certain point you are simply waiting. As long as you don't enter Thailand until you receive your visa it's OK
Nonsense. The DTV is in a separate category. For a tourist visa, you usually get only 2 years but some offices might grant a 5 year license upon renewal to holders of the METV. Might is the key word. For DTV holders, some offices grant a 5 year license upon renewal, others only 2 years.