To the OP: as others have said, you need to rescind right away as your time to do this is very limited--often less than a week from date of purchase. Your contract will have specifics not only on how much time you have, but specific instructions on how to rescind. Follow those instructions to the letter, and mail your rescission letter certified, return receipt requested so that you will have not only a record of delivery, but the date your letter was received. As you yourself have discovered, Westin Desert Willow is available for a fraction of what you have agreed to pay on the resale market. Moreover, within the Vistana system, only a handful of resorts carry a designation of a "mandatory" resort, and WDW is not one of them. What is a mandatory resort? It allows resale owners to retain internal trading rights to visit other Vistana properties through the Vistana system. Without this feature, resale owners at so-called "voluntary" resorts like WDW can only visit their voluntary resort and no others unless they try their luck through Interval International, which is not at all a sure thing.
Already your head might be spinning with all of the terminology thrown at you, and this is just the tip of the iceberg. This whole timeshare thing is incredibly detailed, complicated, and confusing--as the title of your thread implies. I want to encourage you by saying that you're doing a number of things right: 1) if you still have time to rescind and save your hard-earned $$--nice going!; 2) you're trying to unpack this whole timeshare thing and learn what it's all about; 3) you've come to the right place--TUG is a tremendous resource.
You also should understand that it's complicated for a number of reasons: 1) there are many developer companies, all of which have developed their own systems, their own points scales and pricing, and their own rules about reservation windows, upgrade opportunities, cancellation policies, and the like; 2) it actually behooves the developers to make their systems complicated, because they are first and foremost motivated by profit--and if they can keep their owners from fully understanding their systems and squeezing every last penny out of their ownership, that tends to work to the advantage of the developer; 3) the market is dynamic--so that just when you feel like you've got a good handle on things, the rules get changed or new programs are introduced that must be learned all over again. This is happening now within both the Wyndham and Hyatt systems, for example.
The advice you've received is sound. It really will take you months to read and absorb how these systems work. TUG moderators have provided very useful stickies at the top of each of the various systems' BBS boards which will help familiarize you with how the systems work, property locations and points and seasons charts. You should read and absorb those, as that will also help you to begin to narrow down which system or systems you think will best meet your needs for future vacations. Once you've done that, I advise you to just dig into the BBS of the system(s) you prefer. Vistana, for example, while a very nice system with high quality and beautiful resorts, tends to carry ongoing annual maintenance fees that are among the highest in the timeshare industry. As you study here on TUG, your questions will begin to be more pointed, more precise and less general, and you'll have more confidence about making your first purchase--on the resale market.