All of the DVC resorts are quite nice, albeit different in theme. SSR seems as if it is going to compare just fine to the rest. As another poster stated, you'll also get an extra 12 years on the contract if you purchase there.
As far as where to buy, buy where you want to stay. If you like being on the Boardwalk, and close to Ecpot and mGM, then buy at BCV or BWV...you'd probably be doing resale, as I a don't think DVC has any points left in either of those resorts, but check with them directly. If you prefer the MK, then buy at VWL, because you have boating transportation to the MK. OKW is good if you are a golfer, and it's also close to DD. SSR will be close to DD and golf as well.
As far as how many points you need...somehere on this website is a points calculator, which can give you a good idea of how many to buy, based on unit size, length of stay, and time of year. Obviously, the bigger the unit and the longer the stay, the more points it will take.
As far as where to buy from...well, if you decide SSR is the one for you, you can only buy from DVC. The others can be purchased from timeshare resellers...The Timeshare Store is the one recommended by this website, and DH and I bought a resale at OKW through them a couple of years ago with Pat Spell as our agent, and it was quite effortless, very organized, no problem. If you buy resale, you have to come up with a way to finance....I have heard of some very creative financing options. There are folks that have purchased the points using their Disney VISA card and then paid off the card with a home equity line of credit. That way, they get the benefit of the VISA rewards and the tax break of the home equity line. Others have refinanced their home for more $$ than necessary, and used the extra to purchase.
The first contract DH and I bought was through DVC. We took a 10 year loan, with the idea that we'd pay it off in a shorter period of time. The 10 year loan had the smallest monthly payment though, and our thought was that if we had a month where money was a little "tight", we only had to pay the monthly payment. We ended up paying that one off in about 3-4 years, so it worked for us. You really begin to see the benefit of the DVC once you have paid off the loan!
Good luck with your decision. If you are down there, perhaps you could take a few hours to go to a presentation. It is not a hard sell thing, and could really enable you to see what's what.