You burn about 500 calories a day breast feeding. So, if you eat healthy, it should help a lot.
I think it mostly just depends on you.. im 2 weeks post partum i only breast fed for 3 days i havent been doing any exercise or dieting and im already only 3 pounds over my pre pregnancy weight.
It can but it also does help you hold on to a bit of excess fat while you're nursing. Should come right off when you wean.
Yes. It burns a ton of extra calories. As long as your not over eating ofcourse. I went down 10 pounds from my prepregnancy weight.