1. What pc car you using?
2. Yes, you will need some sort of amp or headunit to push your "side" speakers. If you run a headunit you will need one with a aux input...but this will require you to relocate the head unit.
3. As for battery drain...why is your battery going dead or are you worried abou this.
4. What interface of DVDRW will you be putting up front? (IDE, USB, Firewire)
5. Don't forget to search. There is tons of info on this site.