I can clear that up for you. The blue wire is a replacement power wire for the interior electronics lights (in cluster, console stuff, etc.). The raw wire ends (at least the red/yellow ones) are the ends of the original power wire. Somehow, somewhere in the car, the original wire was shorting, and after spending about 3 days with the dash ripped apart, I still couldn't find out what was causing it. I think I may have left some disconnected gauge wires under the dash as well (taped up, not raw), but I can't remember. They would be solid black wire. Your best bet is to just to chase them, they only went a few feet.
To get the lights working again, I disconnected that power wire (red/yellow) where it goes into that system (I believe it is at the light switch) and replaced it with the blue wire (which I do admit I could've run a bit better..). I would have removed the old power wire, but it was bundled deep into the harness throughout the dash.
I'll try to sum it up more clearly. Blue wire comes from where the original power wire connected (at the base of headlight switch), and replaces it. Old power wire is disconnected from power source and components but still in the harness. In response to PR, it is feeding all of the components that the original wire fed, and nothing more. It is still fused properly on the same fuse line and the original grounds remain, simply a wire substitution.
The original reason for the substitution was that that one of the fuses would blow every time I turned on the lights. I can try and give more details if you want. The PDFs in my signature link should contain the wiring diagrams of the dash I used to figure out where the power wire went. It also spiders into the tail lights directly (thanks nissan). It was all a bit mysterious to me, but as far as I could tell either the wire itself was shorted somewhere (causing the fuse to blow when lights were activated), or there was a faulty component which I never found causing the short (but I'm 99% sure I tested them all based on the wiring diagrams). Anyway, the short was after the light switch, and simply replacing the wire from that point on cured the problem. I had always meant to re-wire the car anyways, but hadn't got a chance.
As for the cluster not working, I had that same problem. It might be the relay for the tach causing the cluster functionality issues. I frequently had the tach stick after not driving for weeks, but once it started working again it would generally be fine.
I can explain the dome light, sunroof, mirrors, (and should also be blower motor) working intermittently. It started happening randomly. After wire chasing and testing, I found that the fuse that controls all of that has a bad connection at the bottom of the box. It's not the wire connection to the fuse, but the nesting of the fuse into the metal bracket in the box itself which is faulty. Wiggling the fuse got them to work/not work. It's another thing I wanted to fix but didn't get a chance to (also not sure of the best way to go about it, since I think replacing the fuse box might be a lot of work).
If I remember anything else about the wiring I'll post it up. It sounds convoluted, but actually I really only substituted the power wire and did a poor routing job. Other than that, it's as it was when I got it. I actually had no idea it used to be an automatic... maybe that explains some of its funky issues. Honestly I think the best thing to do for this car would be a re-wiring job with only essential wiring, which is what I really had wanted to do. I think it would clear up a lot. =)