To answer the series question, Tom, the only practical way to wire them in series would be if the lights had two wires, one for power and one for ground. If there is only one wire, and the case is the ground return, wiring in series would require isolating one of the lamps from ground and that is a recipe for failure. With two wires to each light, making sure the case is not part of the ground circuit, wire twelve volts to one light, wire the second wire of that light to one of the wires of the other light and wire the second wire of that light to ground. Thus the current goes through one light to the other and through that light to ground. This would work well enough for fog lights, but you wouldn't want to wire your headlights this way, because if either light fails, the other will not not light. Remember old Christmas light series strings?
