Hi Matt,
yes, "Developed" flag has to be used, "Source" or "Source and Archive" does not count in your case , "Development System Only" is not a must either, it was just a sidenote. No need for RTSs, "Exclude from deployment" does not matter either, since no deployment will take place here, we did not even added RTSs as just mentioned.a
Regarding SCs: there are three type of them. SOURCEARCHIVES, DEPLOYARCHIVES and BUILDARCHIVES.
If you open any SCAs (they are just zip-like archives) then you'll see these 3 folders (or various combinations of them, depends on what the SC is meant for).
What you have to make sure for source comparison is that you import the SCs that have sources (folder SOURCEARCHIVES) and you just ignore the rest of the SCs. This way the time invested into import is minimized, and you don't need to wait for builds. You use the track only for source comparison anyway.
Cheers,
Ervin