FY 2018 Per Diem Highlights GSA establishes the per diem rates for the lower 48 Continental United States (CONUS), which are the maximum allowances that federal employees are reimbursed for expenses incurred while on official travel.
Rice wine vinegar and rice vinegar are different names of the same thing. In order to make vinegar, acetic acid bacteria ferment ethanol, which would be rice wine in this case. Rice wine and rice cooking wine are different.
Mirin is a type of rice wine. It is sweeter than regular rice wine (sake), so if you're going to make a substitution, I would recommend adding a little sugar to compensate for the rice wine's lack of sweetness. Any Asian supermarket or market will sell Mirin (or you can probably buy it through the Internet).