It's hard to say for the walking because you stop and start. I would maybe count 2-6 points, depending on how much walking you did and how intense you walked.
As for eating. there are no nutritional values, so you just have to use the complete food guide and guestimate and move on.
Epcot- Lunch at Japan Teppanyaki is great. I get the combination scallops and shrimp (which is 1 point for 2 oz), veggies are all free, rice is 4 points per cup. Have the dressing on the salad on the side. Count a few points for the oil.
MGM- Prime Time has a wonderful salmon dish. Just omit the fried potato sticks and have the vinagrette on the side, or have them go light on it.
Just go through the menu's and pick the fish, salads, chicken dishes that sound low fat. Veggie dishes are good usually too. Be careful of the sauces and butter that are put on a lot of dishes.
Buffets can even be good if you ONLY eat what you have points for. If you tend to overeat and want dessert, then it might not be good. BOMA's is one of my favorites.
I didn't count points while there, but rather tried to make healthier choices. I still had steak several times and butter on my bread once or twice. While I was gone I only gained .2 pounds (but had gained 3 pounds prior while trying to increase my points prior to going)
Good luck, you will do great.
They have fruit stands at all the 4 parks. You can substitute carrots and sometimes fruit for your fries. Most fast food places have the grilled chicken. Or salads with low fat dressing. 
