1. My base backup folder was "D:\Backups\Registry Backup". This is a separate HDD, with Windows running on C:. Of course, the computer name was added to that path.
2. RegBak restored its own backups, which had the same base directory, except that it doesn't (as I have it configured) add the computer name; it adds a date directory (e.g. "2015-09-18") and under that a time directory (e.g. "10;14 AM").
3. Oops, already answered that one.
4. No. I only ever used VSS. Too paranoid to use fallback, ever.
5. Good question. I wish I had been more specific in my first post. I had to look at my own description of the problem, which was simply: "My own user account did not have access to UsrClass.dat." I should have listed the ACLs. [SIGH] Right now my system is in what I call a "State of grace" and I'm loathe to mess with it. But this never lasts long (Microsoft sees to that). So next time I have to mess around, I will look at exactly what the issue is. Sorry I can't be more specific on this one.
I did just try something, though. I backed up my ID's UsrClass.dat using RB and RegBak, as closely as possible in time. I thought the files backed up would be identical, but they're not. I see two bytes at the very beginning of the file that differ. I retried and the same was true again. No more detail as I assume this is just because of the file being updated normally by Windows.
But another difference was that RB had no attributes for UsrClass.dat turned on, other than the "c"ompression bit. RegBak saved UsrClass.dat with "a"rchive, "h"idden, and "c"ompression. Now that I've typed that, I can't see why it would matter.
The ACLs on both saved UsrClass.dat files are identical, though, including the owners (Administrators).