I would definetly call to make sure it all goes right. I always call them to make ressies, or to change them, because then they go over everything and I know it's all right. The wait this year has not been long.
You can book whatever is offered under Special Offers online at disneyworld.com. These are package and some room codes that are available to everyone. You don't meed a code, just follow the link.
If you are using a pin code or special 3 letter code that was emailed/mailed directly to you, then you need to call. I have booked special offers online in the past with no issues.