When I bought my 85 4runner the previous owner had the headlights and horn and some other wierd stuff wired to aftermarket switches straight off the battery. I couldn't figure out why because all the factory wiring was still there and good. What I ended up figuring out was that the 12 volt relay was missing. It is in the fuse block and is a black square about 1" x 1". After I replaced it and hooked everything back up to the factory wiring it all worked just fine. That may be something to check. It has been years since I bought it so I can't remember if everything you listed were the same symptoms.
