Lots to cover, only a little time this morning. I’ll be back later in the day.
The main point is - most of your worries and questions are covered by the design of the database that MB uses. You are not the first person with a mission like yours, so the ideas have already been sorted through way deeper than you realise. They just need some explaining. It will make most sense when we start adding some data using the examples you have dropped.
The database has a structured way to look after your musical releases. And when we follow that, then any decent media player will play along.
As to OCD - why else do you think this place is here? No sane person spends this long on sorting out music. 
Starting at the end:
This is a MusicBrainz “Release Group”. Under one Release Group you will have:
- The Release on Cassette media with track list broken down.
- CD reissues.
- Radio broadcasts of the event.
- You’ll have a “single file per side” bootleg on Digital Media as is found on the archive.org link at the top of the thread.
- Newer DAT releases that appear of the Whole Gig.
- This would also include your “re-edits” of the CD and Tapes if these are in that same publicly accessible archive.
The idea of a Release Group is editions of the show on different Media are kept together. The theme being the event is in the same group, and each Release will have their own variation of a title.
A Release Group is more normally used to keep all versions of a “normal” release together: CD, Vinyl, Cassette, 10th Anniversary reissue, Deluxe editions.
You are talking “Bootlegs” here really, but the same concept is used. You are kinda lucky that the archive.org folder is publicly accessible as that makes these legit bootlegs that MB will document. If these were just private mix tapes they would not be admissible to the database.
Backups - a quick side step. Go buy an external drive or two NOW. Music is precious. Make snapshots of your music folder and keep them offline. Mirroring hard disks is for hardware failure, not protection against virus or human error.
You also want to take a snapshot now of your archive before you start. As you already know, there will be times errors are made and it helps to be able to go back in time.
iTunes - I’ll keep this short, but don’t build things around that player. It is one of the most awkward out there as it is really just an old shop front. And will soon be abandoned by Apple as they go more online. (Seriously - when was the last time it had an update?) Other threads cover how bad it is handling tags, images and updates. I don’t want to be distracted with that old rant here. 
Music storage - a flat file system is never good. iTunes is a shop selling artists and doesn’t really know what to do with your music. This is why we will find a better way of keeping it on the hard disk. But first we will be looking at getting the data into MusicBrainz. Later we talk Picard and what it can do for you with fancy file renaming scripts. MusicBrainz stores way more info about your music than any player can currently handle. I am a KODI fan and the music side of that media centre is built around MB’s tags. Winamp, Foobar2000, many other better players out there. But lets not go down that tangent yet. We need some examples in the database first. 
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