Hi Caroline,
You must be getting so excited for your upcoming trip! It will be here before you know it.
You can find out which attractions will be closed for refurbishment by looking at the
Park Hours section of the website. On this page, you'll see a box where you are asked to type in the beginning date of your vacation. You'll be able to view the park hours for a 10 day period for each park. At the end of each park's hours, there will be a list of any attractions that will be closed at that time.
Finding a list of snacks is a little trickier. Approved items can change all of the time, so there are no official lists; however, in general, snacks are menu items that are less than $4.00. That's not always the case, but it will give you an idea of what you can expect to find available as a snack. If you want some more specific info, try doing an internet search for "2012 Disney Dining Plan confirmed snacks."
Hope this helps. Have a magical vacation!