Those little voltages don't mean much. Current flowing in a wire can induce current in adjacent wires, and a sensitive meter will show voltage traces if you just hold a lead in each hand- try it.
Bad diode in the CRV harness most likely.
The small variations in intensity of the tail lights when the turn signal is on is caused by the changing current in the ground wire. More current, more voltage drop in the ground wire, all lights dim slightly. Entirely normal, but if it's severe indicates a weak ground.