Glad that you enjoyed your stay at OKW and are thinking of joining
DVC. You've come to the right place as this board has tons of information regarding the DVC. There are no elementary questions regarding the DVC. DVC is a great pre-paid vacation plan for folks who enjoy visiting WDW at least every other year. You certainly fit that criteria. As long as you understand the way that the DVC works, it's a great deal.
You asked whether or not the 11 month window is important. Yes, it absolutely is important. One thing that most of us around here agree upon is the fact that you should purchase at the home resort where you think you'd like to stay the most. If you have your heart set on spending the majority of your time at BWV, don't buy at OKW and vice versa. Presently, owners at OKW, HH, and VB are having a difficult time getting BWV ressies at certain times of the year with their 7 month window. On the other hand, BWV owners seem to be able to get OKW, HH and VB ressies at the 7 month window more easily. So right now, the 11 month window is most valuable at BWV.
Also keep in mind that BWV units are a bit smaller in size than OKW. OKW stays also require the least amount of points of any DVC resort. However, BWV offers a great location that us BWV owners think makes up the difference and then some ;o). VWL point stays are equivalent to BWV preferred view stays.
You asked about the number of points that you'd need to do a 2 bedroom every other year and a long weekend in between at a one bedroom. Well, at BWV, a preferred 2 bedroom during this time of the year will cost you 350 points. A long weekend during the same time in a one bedroom will cost you 180, again at BWV. Keep in mind that there are times of the year when your points will stretch much further depending on your flexibility. Also keep in mind that Friday and Saturday nights are almost double the amount of points that you need for Sun-THurs nights.
Waiting on BCV is certainly an option, but keep in mind that the price per point is most certainly going to rise by the time BCV is completed. We paid $65 a point just 2 short years ago and now Disney is getting $72. Resales can be found for less than $72, BWV a bit more than OKW.
Since you mentioned that you're primariliy interested in 2 bedroom villas might it be possible that you'd bring a few more folks with you and need a Grand Villa? You'll need to consider this question. Just thought I'd mention that the 3 bedroom Grand Villas are only located at OKW and BWV. VWL and the BCV will not have Grand Villas, only up to 2 bedroom. If you purchase points at either VWL or BCV you will have literally no chance of securing a Grand Villa at BWV or OKW. If that's important to you then resale is an option.
I hope this helps to answer your beginning questions. I'm sure you'll have more in the near future. Keep asking!!
Laura