Thanks guys, I think I have a plan now. I have on hand a 40W iron, oxy-acet setup with small tips, and some experience in silver brazing small parts- hopefully some of that skill set will cross over to heavy duty electrical soldering. I`ll be sure to order plenty of extra connectors to practice with- might be able to handle the 16 g stuff with the iron, and will buy a heavy duty "dimple" crimper if need be (but the "butt crack" crimps sure do look cool!)
I will also order a ground bus. The hot side I will think I will just make soldered Y splices rather than a hot bus. Since I have two constant and two switched circuits, that makes one Y before the relay and one more Y on each of those ends (one between the relay and the fuses, one more on the original line just before the fuses). At least that`s what sounds best to me. Reasonable or silliness?
Nothing special to worry about concerning wire? I like the selection at West Marine because they sell 14g and 16g by the foot, so I will be able a different pretty color for each hot lead without mortgaging the house for a whole spool of each color.
I have today off work, will use part of it to draw up a whole proposed schematic including all wire gauges and fuses, all the switches, and connectors, the relay with base, then I can put in my orders. I`m including E.B.`s prebuilt headlight relay and switch harness because there`s no way I can match that.
As a last thought, GW`s mention of Radio Shack nearly brings tears to my eyes. We used to have a half dozen Radio Shack locations in my area, not one left within 50 miles now. The local electronics supply place also closed, so now we only have my friendly neighborhood True Value (and thank God for them) and auto parts houses for anything Radio Shack-y, or drive two hours each way to Frys in Sacramento. Otherwise, it`s order and wait, little chance to run out and pick up a little something that you forgot about.