How to sift my image library

This is iteration 54231 of this question, I'm sure, but for your amusement...

I have a large number of digital pictures, most likely a subset of which are in the Photoshop Elements Organizer. I'd like to

-- start removing duplicates, which I would classify as same file name / same date taken / same file size

-- a side benefit of this would be that I'd get a list of pictures scattered across my disks which are NOT in PSE, which would hopefully be of a small enough number (ho, ho, ho) that I could pick through these at my leisure, deleting any that might be incriminating <g>.

-- after that, insert GPS map images if the pictures have GPS data stuck up in the EXIF, for those times when I go back and think "Oh, nice. WTF was this ?". There's the hand-include of info from Garmin that would also be useful.

-- determine for future use whether PSE Organizer is really the place to store this info. I'd rather not build a RYO solution unless pushed to the edge of the cliff, but there may be things that would be nice to have that I just haven't thought of needing yet.

Autotagging with the camera make/model would be useful as the pictures cover at least a 25 year interval (slide scans would stretch that to 40+, but before the digital camera of the month I can pretty much attribute them all to my ME Super), esp. because the Nikon P610 and the Canon SX280 are orientation-ignorant ; being able to pull all of those would allow some (tedious) sessions of "rotate left", "rotate right",.

Given that I have "stuff" in PSE, I'd like to be able to read the catalog for the information contained within,  but the way to do this is apparently super secret information, so if there are any hints / roadmaps around that would be helpful .

Should I have to go to RYO, an alternate universe solution probably has to live in MariaDB or PostgreSQL insofar as Oracle looks like they're going to torpedo MySQL