Can someone help me understand the whole Star Wars print history?

I’m just curious about the backstory of this, as for a long time these projects have just been cobbling together rips of retail releases and TV recordings.

How did full 35mm prints of the movies turn up? How many are out there in the public? (Because I assume having them, or access to them, is uncommon?)

Does what Poita or TeamNeg1 have represent the best available in public?

I know this information is somewhere, but I wouldn’t know where to begin to find it here in the forums. I can’t say how awesome it is that this is happening. I donated to the cause and would do so again for an archival, historically accurate (as much as possible) set of the OT.