Alright, the fuel tank is removed and drained. That was an interesting bit of mechanical Tetris. It looks to be in remarkably good condition - I can't really see any rust.
No luck on the dash lights, but for the horn, I did find a disconnected wire on the junction block next to the driver's side horn. I highly suspect this to be the culprit but didn't get to reconnecting it today.
I've been having a lot of fun watching the video you linked, Sirrotica. My engine bay looks a lot fuller than theirs, I think due to a/c equipment, but you'll be able to tell better than I from the pictures.
Tomorrow I'll get a gallon or so of gas and rinse the tank, then re-drain it. The tank drain plug tries to leak, so I'll replace the plastic washer if I can find one. What should I do (if anything) to the fuel pump? I assume replacing the fuel filter is a given, but I haven't been inside a fuel pump before. Goatracer mentioned something about a 'sending unit' to be addressed while the tank was out, too. Also going to locate that fuse box (thanks for the tip, Larry) and replace any bad fuses - most are 7.5 amp, according to page 12-34 in the Shop Manual.