1) yes 2) Fine you will have no issues. That is what the visa is designed for 3) in theory CC Cards spending is included in remittance according to a few tax advisors. In practice I have more chance of dating Margot Robbie.
As others have suggested contact the Embassy. It is known to be a stickler for the rules but it is also very efficient. If all docs are aligned they process quickly. Good luck
Great you got it done. I think your agent got around the "Rules" though rather than being changed but so what if it worked. It is usually a long term residency or with a 1 year WP or a Thai returning home. Does not matter though if it worked for you.
They are generally 90 days for eVisa and 30 for older types. The poster says they arrived 18th and only had a visa till 25th. How is that possible? :-)
I do not understand the length of the Vietnam Visa either. Do they even issue a visa for a single week? Most common is 90 day e-Visa and older ones are 30 days.