Deck fittings are installed before the cap is fastend to the hull. So that length of wire was probably run from the bow pulpit when the stations were mounted, my guess is it runs down from the nearest stantion to the light on the starboard side.
You seem to have a good grasp on what is needed. You mentioned a piece of aluminum plate welded to the skin. I'm not a welder but I suspect that the various thickness between the two may be problematic.
It doesn't take long for that mess to get circulated and rust things and if it's coming out of the valve cover breather tubes you can be sure it's everywhere.
You shouldn't need to go to 4400, 3000 and it should be fully advanced. If you're familiar on how the advance works you need to insure the weights move freely a drop of light oil on the pivots and check the spring's are ok.
