The plane codes so far as I know go like this:
Code:
MC-202
MC-202_III
MC-202_VII
MC-202_XII
The first one on the list is the original MC.202 model that shipped with FB. It's not as high quality as the others, it has no cockpit, and it has a much poorer damage model ... there may be other issues with it. It's there for compatibility sake so far as I know. They all use a hyphen instead of underscore... that seems to work with other aircraft codes as well.
Not sure what exactly you're asking about in the hsfx part but I assume they use the same codes that the rest of IL-2 does.