Leonie to save the day again! :-)
I don't really have a reason to think other software is causing the issues. Essentially the story is this. I created a new library (my first one ever) and started dumping acres and acres of photos/videos in to it for permanent storage from what used to be a simple hierachal date-based folder structure of media. I got about 200GB in when randomly, the library started showing me different errors about how my database needs to be repaired. At first, I was excited to repair it thinking to myself, how awesome is this for catching it?! Upon repair, a large chunk of photos and videos from nearly every project in the library was mercilessly thrown in to a "recovered" project which I have no intention of working from. I'd rather just go back to the source and start over. (Sigh.) I then recovered the last known working library from Crashplan and tried working in it again. A few days later, the same thing happened, but this time the error was something more along the lines of "several crashes in a row might mean you have inconsistencies in your database." This gave me 3 repair options. Needless to say, the first two options didn't fix anything and the third dumped many of them back in to the dreaded recovered project. So I'm essentially at a loss with that. As to another question of yours, it has worked for a month or so when I was initially building the library, so in short, it does work when a few test photos are in there.
You also mostly already answered my next question; does exporting projects and importing them to a new library 1) preserve the original image quality 2) preserve tags/keywords and the like. I assume the image quality will remain preserved as well?
I'm assuming that if I took the broken library and exported everything that isn't in the "recovered project" area that this would keep the troublesome part of the library out of the new one, leaving me to just manually re-do the troublesome parts of the bad libary from their original source in to the new one.
The only thing that would possibly make sense in the troubleshooting you've listed might be the plist which I haven't yet done. I often open my library via the network as it's stored on either my iMac or my thunderbolt storage (Drobo 5D). I say this because I've tried this on both. I'm running today's version of Aperture 3.