Have to put in a plug for the "Have Freak, Will Travel" Mutant Vehicle parade (Friday night DURING sunset).
More info will be posted at the following link once the date gets closer.
Now for questions/answers:
Do you want your shells to be permanently fixed to your vehicle? If so, super glue is great; your weakest link will be the paint. One hint for anything permanent or temporary, make sure the surface is clean. I use cheap rubbing alcohol. For permanent, it's best to apply pre-playa. That dust you love to hate is hard to clean even at home.
2) EL Wire
Not sure where the best place to buy is; I'd just do a net search.
Here's a few:
http://www.nathanielwandering.net/Burni ... 0Links.htm
EL-Wire is high voltage low current, so your 12 volt car battery will not work directly. You might be able to buy an "inverter" that deals with 12v DC.
If you want blinking or "moving" effects, you will want to get a sequencer. The sequencer and inverter are usually bundled together, so decide and make one purchase.
The EL wire connections are delicate, so make sure to fix them so they don't get yanked.
See you on the playa,