Hi Julie
I believe that I've heard that soy protein is not a complete protein so as an after workout shake it's not as good for you as a whey protein shake... Yes, it is good to have protein after a workout, and shakes make it easy, but real food is always best. You can eat chicken, cottage cheese, beef, whatever meets your fancy... I can't answer your question about the WW plan though, but I can say if it's within your alloted points, I guess it is ok
... Sure it's ok to lift the day you weigh in but don't be surprised if you weigh more after a workout because your muscles are pumped a bit from the workout...