Need help with headlight/taillight wiring

[kola]

Hi:

I purchased a painted cart body with the after market headlights and taillights already cut-in. The lights and harness have connectors that make connection very simple; however, there are separate wires that I don't know what should be connected to.

1st Picture: These connectors off one headlight and marker light.
2nd Picture: Connectors from wire harness to headlight and marker light

It's pretty obvious the two white connectors mate up one each other and the green female connector off the marker light mates up with the red male connector off the wiring harness. Where does the flat connector with black wire coming out off the wiring harness go? Is this the marker light ground? If so, where is the typical place to ground?

3rd Picture: These connectors are off one of the taillights. Again, it's obvious the white connector off the taillight mates up with connector on wiring harness. However, there is an extra (red) wire that comes off just one of the taillights (2nd does not have similar wire). What is this third (red) wire?

The last picture is of the on/off switch to maybe help identify the manufacturer of my lights and harness.

I'm going to also install turn signal kit and brake light kit, but want to first ensure that I get the headlight/taillight wiring correct first

Appreciate any assistance that can be provided.