What hardware do I need for intensive video editing?
 

I need some general info regarding how processor type and speed, type and amount of ram, and type and speed of hard drives affect video editing and exporting. What are the most important elements for efficient running of editing programs while edited HD footage? What matters most for increasing export speed?

Chip speed will be the most important. Build your setup around a quad core.

Next up will be ram but it's a fairly distant second in my experience

And to add to Dan's post, an big external hard drive to store it on or you'll bog your computer down pretty quick

How does a single quad core versus double quad core compare?

Also, how important is hard drive speed for exporting?

Don't know about the dual wield quad cores but hard drive speed doesn't factor into the export. More import is transfer speed (such as copying to a backup drive). eSata is faster than FireWire which is faster than USB 2.0.

And what is a good RAID setup to use to maximize editing performance?

Generally, bigger and faster is better...but specifically, you should check the system requirements that each NLE maker provides for the particular program you may use. Adobe, for example, posts very narrowly drawn specs for the video cards, amount of RAM, operating system specs, etc for Premiere Pro versions. The latest, for example (CS5) is 64-bit only, needs one of several specific nVidia boards to use certain features, and a specific (large) amount of RAM. Final Cut has it's own specs (Intel mac, etc). So your question is too general -- figure out your editing software needs and then let the maker of that guide you to the specifics of the system...