I'm not on WW, so I won't even attempt to address that!
Just wanted to say that when I go on vacation (esp to WDW or DL), I know I walk a minimum of twice as much as I do in a normal day, but usually it's more like three times as much (sometimes even four), so I allow myself a little more leeway in terms of food.
I think even if you decide not to be strict about sticking to your points that you should count points for whatever it is you eat anyway, just to give yourself an idea?
But, there are so many dining options at WDW that I'd bet you'd be able to stick to the plan without many problems. I've heard that most WDW restaurants are pretty accommodating with substitutions and such when asked too.