I wish I could give you advise on the wiring but I have no clue. The best I can offer is to track it all the way down to get a feel for the way it is ran. I could be wrong but I would imagine that it would be locked down somehow along the way with some form of a clip.

As far as your bed bolts go, that's the fun stuff. I would recommend using a long handled torque wrench with the proper socket that fits and exact fit for the bolts. A long handled torque wrench will give you the greatest amount of leverage I beleive on those bolts. I think on my truck it's a Torx that is required, I'm not sure on your truck.

If the bed bolts have never been removed to your knowledge then I would first just go ahead and soak down as much of the bolt as possible with an agent like PB Blaster. Even if it's just the head of the bolt flush with the bed I would still hit it. Put on your wrench and try to begin backing off the bed bolt.

From your post it sounds like you expect the bolts to be full of rust so don't just back them right off. Pull them back a bit then sink them back down a little. Kind of like a back and forth motion which should allow the rust and contaminants to come out of the threads. When you don't go back and forth as you back the bolts out, that is usually where they will break off. It's kind of like using a tap, if you just go straight in, especially with smaller taps, without letting out some of those shreds of metal then it's going to break your tap.

If you are going to use the same threaded holes for the new bolts I would defenitly recommend getting yourself a tap and cleaning those holes out. I would also recommend that you use anti-seize on your new bolts.

When are you planning on doing this? We don't live to far from eachother if you need a hand.