With the days you will be in DL/DCA area (Mon 12/2, Wed 12/4, Friday 12/6) you should be able to see a lot of the sights if you get to the park at opening and take a break in the afternoon. The first few hours of opening are very low crowds and you will be amazed at how fast you can ride rides. Monday and Wednesday should be fairly slow, but Friday gets busy in the afternoon. That weekend 12/7-8 is the candle light processional and it should have moderate crowds.
I would think that if you went Sunday 12/8 first thing in the morning you could get a lot done before heading to the airport. Sat 12/7 will be buiser than a normal "off season" saturday due to the CLP. DCA should be slower than DL that weekend, also.
For the Light parade, I would say 45 minutes to a hour should give you very nice seats. We showed up 10 minutes before start and had standing area behind the first row of sitting people. My mother in law was able to sit in front of the tree next to us. Kinda in the road, but she didn't get run over or anything.
Any place along the main walkway (sunshine plaza) is good. There are some benches that are fairly close to the street and some planters that are raised that would be nice to sit on. I noticed when we were there that at the beginning of the parade route there is no curb. The sidewalk is the same level as the street, so it was a bit uncomfortable to sit on the ground. I didn't notice if there was a curb towards the end of the parade route.
DTD has a few "take out" kinda places. One is Wentzels Pretzels. They have different flavor pretzels and a hotdog wraped in a pretzel. We got 3 pretzel dogs, 2 speciality pretzels, a slurpy type of drink and it was a little less than 20.00
Then there is a window at Napels Pizza Place. For 5.00 you get a large (plate sized) slice of pizza and a soda. I enjoyed the pizza here and had it a few times. My girls (3yrs and 2yrs) each ate a whole piece for dinner. It might be cheaper to just buy a whole pizza, but we liked the different slices. I loved the Veggis one and the girls ate the cheese. My husband like the Combo. It is thin crust, with a nice red sauce.
There are benches all over DD and we just sat on a bench and ate dinner. There is also a Haagen Dauz (sp) that is very yummy and the line moves fast, even though it looks long.
Inside The Grand Calirornian hotel is White Water Snacks. They have muffins, sweet rolls, salads, made to order hamburgers and chicken sandwiches. Good food and inexpensive prices for the DLR area. GC has an entrance in the middle of DD and is very easy to access.
Disneyland Hotel has a Goofy's kitchen, it's a character buffet. I don't know if that what you are looking for, I have never been to WDW.
Hope that helps.
Sonya