Rosa,
No, the free Dining Plan promotion will not make it unbearable when you visit. It certainly will cause the crowds to be a bit larger, and you will want to make sure that you make your Advanced Dining Reservations for any table service meals that you would like to enjoy, but otherwise I would not let it worry you. October is normally a pretty average crowd month, so the added attendance will be noticeable, but not too bad, I would think.
As for the weather, the National Weather Service reports that in November the temperature and rainfall is as follows;
- Daily Average Temperature: 68.8 degrees
- Average High: 78.9
- Average Low: 58.7
- Monthly Rainfall: 2.32 inches
So the rainfall is very low. The temperatures might mean that you have the occasional day where swimming is not ideal, but from past experience you can assume that you will get several days of good swimming weather. Also, since the resort pools are heated you should be fine. Finally, the nightly low temperatures make me think that a light coat or sweater will make your evenings much more comfortable, so pack accordingly.
Have a magical vacation!