It depends on how much you bring in they have tax brackets, but it will also depend on personal situation for example. I will never pay taxes on my income from the US due to a treaty signed between the US and Thai government DTA, thailand will not tax entitlements/ benifits that are paid out by the Federal Government such as retirement / Pension at the federal level or Compensation such as VA disability
Yes, you have to be out of the country to process once approved leave thailand with the dtv letter come back in show it to immigration and you get a DTV stamp. Can be same day most goto Vietnam and come back
If you are married and military ( if in US military) you will update your info in deers to show marriage and process family move there as well for visa you will have to go through state department to get her visa process.
several students at my school they are cracking down on accounts, some have some havent. But what I do know is that DTV or Ed visa ( non university ) can not open accounts at the moment.
I really don't care what you belive its my stance people like you are not even here and or just troll.