Concerning private info, there's no way to indicate this in the GEDCOM standard. The main purpose of the boxes in FTM is so that FTM can privatize info before you export it to GEDCOM. I believe some apps use curly brackets in the GEDCOM to mark private data, but that's not standard. About all you could do is include the word "private" in the fact note for each fact that is private, or something like that, but there's no easy way to find or filter private info that I can think of.
No, nothing in the standard, but we all know about the standard's limitations. It's good the authors had the foresight to allow vendor defined tags. Unfortunately, it's also the most widely adopted transfer mechanism we have at this point, since the other attempts at newer standards didn't really find any adoption by anything other than a few open source programs. That's the most likely reason for FTM's liberal use of the vendor specific _* tags like _PRIV that FTM already uses for media marked private in some variations of their gedcom export.
I'm not sure I'd go out on a limb and say:
"The main purpose of the boxes in FTM is so that FTM can privatize info before you export it to GEDCOM"
It looks like FTM and RM7 utilize this setting much the same way. It provides users a way of hiding certain information in general program output. So not only is it optionally hidden in gedcom, but also optionally hidden in reports, books, website output, etc...
RM already has a corresponding private field for facts (though not for media as you've pointed out). Unfortunately, we'd need cooperation from FTM to export the _PRIV tag with their gedcom for facts and some help from RM to import it and apply it. I doubt we'll get the former, so the latter probably won't be needed, but it's great to see RM being very responsive and helpful to its (possibly) new user base.
My message was just to let people know who may have used the Private checkbox on facts in FTM (like me occasionally and now I'm glad I didn't make extensive use of it), that those facts will get published in their output should they publish/print/export any of their data from RM7. No fault of RM's, FTM is not providing any knowledge of the setting in the gedcom.
Unfortunately, after playing with FTM's reports there doesn't seem to be an easy way to determine who has private facts or what they are on each person. You pretty much have to know what facts you possibly made private (either as a default setting on a specific fact or by setting it individually on a fact) and then make the same changes in RM. The Custom report is as close as I can find at the moment, but I find I am still doing some visual comparisons. If I come up with a decent way, I'll post it. Happy New Year everyone!