Questions about shaoxing wine
All the other information presented here is correct and the main problem is liquor licenses. I use the salted variety often out of convenience and price, but it is a lower quality and well, heavily salted. Typically, if I'm using the wine, I'll just reduce salt elsewhere.

If you can't find an unsalted variety and really want something that works well, as an alternate suggestion you can use a dry sherry. It will usually be cheaper than a proper bottle of unsalted shaoxing wine. Note that sherry will also come in salted, cooking varieties and similarly you don't want those.

If you live in an area where the liquor licenses aren't a problem, I hear good things about the Pagoda brand.