1. If the pink wire is labeled fuel sender then that is what it is. 2. "Power to gauges" should be in the harness? If not, power comes from run. If you look at original posters pic, the red wire says "gauge power" and is chained to all the gauges. looks like it is part of the harness. There is a hint of this in your 3rd paragraph. 3. Voltmeter: good move.
If you need further info: Remember, I asked for harness part number and all instructions and diagrams/schematics.
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn