Can I use a four pin ballast resistor in my two pin car? It was suggested that I could use two of the pins at a time, then if they failed switch the terminals to the other two to get me home. Does this sound right? Need electrical help! Thanks.

It will work. However, not sure if the voltage difference is something that will give problems down the road.

No, this will NOT work properly. The two resistors in the four-pin unit are of very different resistance. Just carry a spare 2-pin unit in the glovebox or, if you want, bolt the spare to the firewall.