Hi,
Magnetic waves are not the same as atoms and i dont think are affected by temperatures within reason, even absolute zero. If you pass the light through an ultracold gas of sodium atoms bathed in laser light however you can slow light down by a factor of 20 million (something like 38 miles per hour).
If you look out the front window assuming everything else stayed the same, you should see whatever was in front of you. If you are traveling backwards however, you should see nothing because the light would never reach you.