I think you have a great plan. October is a wonderful month to visit, and the projected completion of the DCA renovation is "Summer 2012" at this point. So, arriving in October is a great way to see all the new stuff without the crushing crowds of the Summer season.
I think 5 days is just enough time to see everything.
Good luck booking GCV. It's a wonderful resort! If you can't get in there, though, the Disneyland Hotel is a great second option, and you can use your points there.