The people on these boards are at least as much DVC experts as any CM or guide you're likely to talk to... and more likely to give you straight answers.
As to your questions, unfortunately, the answer is "it depends." Yes, it is sort of like owning a timeshare, but you don't own a week or a particular sized unit, you own points. It costs a different number of points to stay in different sized units, in different DVC resorts, at different times of the year. There isn't really any way to talk about DVC without talking about points.
As far as how much money you are shelling out, well, it also depends. The minimum number of points you can buy from Disney is 160. That is roughly $16,000. What would this get you? Well, it depends. A week and a bit in a studio every year at just about any DVC resort, any time of the year. 6 nights (5 weeknights, 1 weekend) in a 1 bedroom in less popular times of year, or the 5 weeknights in the 1 bedroom most of the year. About 5 weeknights in a two bedroom. The problem with explaining it is that all nights have a point cost associated with them. Weeknights are cheaper than weekends. Studios are cheaper than 1 bedrooms, which are cheaper than 2 bedrooms, which are cheaper than Grand Villas. Some resorts (like BLT, the new DVC resort at the Contemporary) cost a lot more per night than others.
As to taking out a loan for it... some people do so. It is a heated topic of debate on this board. There are people who will tell you not to finance it, it is a luxury purchase. There are also plenty of people who choose to finance it.
To complicate matters even more, you can buy fewer points for less money resale, but that gives you fewer financing options. If you start with fewer points, you can bank points from one year and borrow from the next year so that you can use three years points at once.
I know it sounds confusing at first... it is complicated, but very flexible. Just keep asking questions here on the boards, and you'll get great info.
