I'm guessing...
1-4 -> from Big Big World EP
16-19 -> live at SXSW '97
the rest -> outakes from Big Big World & Rejected Unknown sessions?
Favourite Darling Girl was the only song with the Rats that made it onto Rejected Unknown...
Overall, good guessing!
One of the Rats (either Will Indian or Rusty Trapps) told me awhile back that they were recording more material with Dan and putting out an album soon of their output together.
This would be it. Some notes:
Brian Beattie has told me that the Rats only did two other songs with Daniel while he was at the board, and that both of them were unreleaseable (at least in his opinion) for one reason or another - I think what he said was that one song they worked on never came together, and the other one I'm not so clear on but it may have been that Daniel didn't like the results of the session.
Among the EP outtakes, some are definitely filler, with Dan doing spoken stuff over what I'd call bad "jazz odyssey" instrumentation by dem sloppy, bloozy Rats. The version of Worried Shoes here is one of my favorite Daniel recordings EVER, with very different lyrics and arrangement, plus a long, sentimental spoken part in the middle. All of the titles listed from #1-14 correspond to recordings that exist from the 1986 sessions.
Also, the Rats have recorded and/or issued their own versions of Broken Dreams, Speeding Motorcycle and Wicked Will before -- I'm guessing that these are those tracks and will not feature Dan, despite the official description of the project (unless maybe they went back to the multitrack master tape and recorded new vocals by him, but that's not really the sort of thing I can imagine him being eager to take part in -- it's just not how Daniel works).
As far as your guess about trax 16-19, those are indeed the songs they performed at the "comeback" show I set up*, but I was not aware that any recording existed aside from the home video which Daniel's dad shot from the back of the venue - the audio on that would leave very much to be desired so let's hope there's another source or that these are studio tracks!
- Not Daniel
*This was when everyone was insisting that Dan would never, ever play live again, so it was announced as a Not Daniel Johnston show. That way, we assumed that people would figure out it was really him, but if he flaked I could do my set and noone could claim false advertising! There's a review of the show at:
http://www.sfbg.com/Music/31/25/capsules.html The critic's description of my physical appearance is not exactly flattering, but at least he didn't call ME a "freak".