– I’d like to keep that Photos library with referenced photos, and perhaps open/view it in Photos on occasion, but I’d like my main photo organization/editing software to be RawPower. I assume such setup is possible (based on what I saw in this forum and in the manual). yes?
Yes, RAW Power supports referenced files in Photos. It also supports just files in the file system (Finder folders)
– I’d like to continue adding to that same library, and all newly added photos will also be referenced, residing on an external drive. Still possible, right?
Sure, that’s fine.
– Since all of the existing photos in that library were processed/edited with Aperture, and all the new ones will be processed/edited with RawPower, how would I be able to tell which are which? Is there a (easy/simple) way to differentiate these two groups of photos? (due to the Photos limitations that Nick has highlighted a few times, I don’t want to try to edit old/Aperture photos with RawPower and new ones with Photos).
No, there isn’t an easy way to tell them apart. Photo marks Aperture images as “externally edited” – it’s technically possible for the app to tell the difference, but not efficiently.
– Finally, does RawPower have any support for videos (at least so that videos can be displayed/played back within RawPower, similar to what Photos tries to do)?
Yes, videos are supported in RAW Power. You can rate and flag them too.