We do one large suitcase (under the 50 pound mark) per person. Then we do one more suitcase for extra sneakers, non essential toiletries, and a sweatshirt for each person. We do laundty while at WDW and have nver had a problem packing what we needed on SWA.
As for food - we do not pack cans, glass bottles, or knifes.
We do a small food shop when we ge to WDW. We buy a small jar of mayo (refigs in room now), a cheap can opener, a cheap paring knife, some cans of tuna (one dinner in room after a long day at the park), crackers, snacks, and fruit. We also pick up about 12 water bottles.
You could also ship a box of food to your resort. Remember to say to hold for "Your Name" and your arrival date at the resort.
The Disney Florist has a nice selection of fruit, cheese, snacks, cookies, soda, wine, water bottles which can be sent to your room in a nice Mickey bag, or Mickey basket, or ..... with Disney plushes, balloons....
http://www.ftdfloristsonline.com/waltdisneyworldflorist/