First, do your research before buying. Peruse the DVC threads, read various views on what's important and what's not (you'll get conflicting notions, but that's part of the education process). Beyond that, keep in mind that in the end only you can determine what's right for you--it might not be DVC at all. With those thoughts in mind, here are my initial reactions:
1) Resale vs direct buy will likely engender the most discussion. Certainly, the least expensive route is to go resale, especially given that you're aware of the restrictions regarding DCL, etc. However, there is the school of thought that if DVC ever does do more restricting, it would be with those with resale contracts, though in the past they've grandfathered contracts bought before a given date.
2) Keep in mind, however, that no perks to anyone are guaranteed. Perks, like water in the desert, can evaporate (and have as many would argue). The decision to buy into DVC should solely rest on whether it works for you family in terms of accomodations now and in the future. All you would truly be doing is prepaying for deluxe accomodations over the next 40 years or so.
3) Month and resort do matter, especially the latter. You want your points available each year so that you can book 11 months out at your home resort during the timeframe you can visit. Keep in mind, though, that your situation may change in 10 years or 20. That's very hard to foresee, naturally. Back on point, you shouldn't buy a contract for a resort at which you would mind staying. At the 11-month point, nearly always you'll be able to get into your home resort, but it gets dicier at the 7-month point, especially if you are locked into a particular time during the year. Here's a good example. We own at VWL, meaning we can book for the Christmas holiday season 11 months ahead. VWL is perhaps the most popular resort during the holidays due to its gorgeous theming, so at the 7-month point it becomes extremely difficult to secure a suite there.
Thus, if you buy at SSR, but only mildly like it, you might be disappointed come 7 months out and you're attempting to get into BCV for a summer date or BWV for the Food and Wine Festival yet no rooms are available. In short, love where you buy. That way, if your 7-month request doesn't come through, you won't have any regrets. We love VWL, and we've had fairly good success at getting other resorts at 7 months out, but those times when we haven't succeeded, it didn't matter since we do love VWL.
One last note about resale vs direct buys. Disney has direct options for most resorts, even the older ones, but they aren't as numerous as the contracts you'd find resale, and you will pay far more for them than via the resale route. On the other hand, there are no restrictions on those points; you generally get the points right away; and if you plan to finance, Disney is far easier to work with.
Hopefully, these few notes will help you come to an educated decision. I'm sure others will offer links and advice--take each with a grain of salt. Good luck!