I can't answer all of your questions, I can only tell you what's working for me.
My first 5 weeks (ish) of SB I didn't exercise, or only once a week. I lost 6lbs, 3lbs (both Phase I), 0lbs, 1lb, 0lb. Then I started exercising, and even though I was eating more whole grains and fruit, I lost 2lbs, 1lb, 2lbs. It's helped me a LOT, and I really enjoy it. My program is basically 3-5 times a week, at least a half hour of cardio, and I'm just starting to add in weight training. Eventually, I want to do more, but I don't want to push myself over the edge and quit, KWIM?