The cost is hard to describe until you are familiar with the way the system works. There is an FAQ thread near the top of this board that should help you a lot.
I would also order the video from
DVC. They are no pressure sales, so don't worry about getting on their list.
As to where you can stay, DVC has villas at Hilton Head adn Vero Beach and on-sires at Old Key West, Saratoga Springs, Boardwalk, Beach Club, and Wilderness Lodge.
You can also use points to stay at Polynesion, Contemporary, Grand FLoridian and Animal Kingdom. I think the mod's too. This is not as good of a deal, but still an option.
You can also trade out to
DCL and Disney Land using points. Again, not as good of a deal. Finally, there are places all over the world that you can trade out too.
Popular opinion here, though, is your best bet is to plan on using your points most of the time at DVC villas.
Go ahead and read the FAQ and let us know when you have more questions. It's a lot to digest, but you'll find these boards have a plethera of good info.
FYI - If you go at least once a year (or maybe every other year) and stay at delux, DVC is usually a very good deal. For mods, it's not as much of a bargain, but you'll be in better than delux accomodations (all villas have at least a kitchenette and access to free washer/dryer), 1BRs and up have a full kitchen and w/d in villa).