2. RootsMagic stores FS ID's (into a different part of the database than FACTS) apparently DURING -or- AFTER the AutoMatching process.
RootsMagic stores the FamilySearch ID's into a different part of the database than facts AFTER the matching process. The matching process can be manual or automatic, and the storage of the FamilySearch ID's is the same either way. I think that after the matching you can't tell if the match was achieved manually or automatically.
From a relational database perspective, the linkage between the FamilySearch ID's and the RootsMagic RIN's is achieved by a JOIN between the PersonTable and the LinkTable. The LinkTable stores the FamilySearch ID's, and it includes the RootsMagic RIN for each FamilySearch ID. The RIN numbers are used for the JOIN. It's a similar concept to the way RM stores names. Names (including Alternate Names) are stored in their own separate table, and the linkage between names and people is achieved with a JOIN. The difference is that names are presented in the Edit Person screen as if they were facts, even though they are stored in the NameTable instead of being stored in the EventTable where facts such as birth, marriage, and death are stored.
I suppose it would be possible and fairly easy for RM to show FamilySearch ID's as facts in the Edit Person screen, but you wouldn't want them to be able to be edited from there. They should only be able to be "edited" by going through RM's standard Family Search interface. And I suppose that it would be possible and fairly easy for RM to make Family Search ID's available to RM's searching and marking dialog. Names are certainly available to RM's searching and marking dialog, even though they are not stored in the EventTable. Searches such as FSID>Exists>Is True, FSID>Exists>Is False, FSID>Contains, etc. would be very useful. It's the sort of thing that's extremely easy to do in SQLite if you are able to use SQLite, and which is not really possible in the RM user interface. Well, you can get a list of FSID>Exists>Is True simply by going to RM's FamilySearch interface. You will see a list of matches. But you can't do things like FSID>Exists>Is True AND Birth>Date>Is Before>1900 or anything like that.