Do I understand this banking/use yr stuff???

[sndral]

I am eyeing a couple of offerings for my first attempt at this - so first question, I think a Sept. or October use yr. would be best - we travel in early Dec., starting the weekend after thanksgiving weekend usually early Dec, very rarely a day or 2 at the end of Nov. falls on that weekend. Am I correct that Sept./Oct. is a good use year for those travel plans - I doubt this will change, as I go to see the Xmas decorations.
There are 160 pt. contracts advertized at 2 of the big 3 DVC sellers both have some 2012 points, all 2013 and all 2014 points. One is a Sept. use year, the other October.
This is what I think I understand, using Sept. use year as an example:
2012 points must be banked by 4/30/13 and can be used from 9/1/13 to 8/31/14?
2013 points can be used from 9/1/13 through 8/31/14 or banked by 4/30/14 and used by 8/31/15?
2014 points can be used from 9/1/14 through 8/31/15 but can be borrowed for use from 9/1/13 through 8/31/14?
If I am hopelessly confused (this stuff makes my head swirl) please explain what I am misunderstanding. If it helps, we won't be going in 2013 (we are skipping a year) and our next trip will be 2014 - early Dec..
Thx.