What are you hoping to get out of the membership? How often do you plan to visit Disney World, and for how long? Is WDW even your main interest, or do you plan to take advantage of the other options (RCI, DCL, Adventurers Club, etc.)? You need to give us some more info on your intended use, along with what's confusing you, before we can offer much assistance.
You are buying pre-paid rooms at a DVC resort. Money up front plus yearly dues and the desire to vacation primarily at WDW every year or two for up to 50 years.
(there is also a resorts link above that you can use- look under the villas section.)
if you call to book your home resort at 11 months out, you will virtually always get what you want. if you wait, results become more variable.
there's a link to point charts for the different resorts in the top right hand corner of this screen.
(the point charts show the price - per night - in points. there is no discount for a 7-night stay and it doesn't matter if you start in a different season, just add up the point cost per night as listed in the charts to figure how many you need.)
for further reading, here is a good thread to start with: