'33 1003 headlight and horn wiring help

I need the proper connections for the headlight wires on my '33 1003 Su 8. The plugs in the base of the headlights are labeled 1-2-3-4-G The right light has connectors in 1-2-3 and G, and no connector in 4. Thus, I assume 4 is for parking lamp if not equipped with fender lamps and G is ground. The left light has connectors for 1-2-G

I also need to find a source of the small "bullet" terminals for the wire to plug into the base of the headlights.

I am confused on the horn wiring - as both a hot wire (from the generator cable in the harness) and a ground wire (from the switch) are shown to be routed. One wire remnant is going into the horn cover to a terminal. I am unsure where the ground wire connects. This would imply that the horns are insulated from the body ground, but I do not see how.

In '34 Packard (wisely) used a horn relay. I may add this hidden improvement and solve my problem.

link to discussion on Packardclub.org