It doesn't work for everyone. Some women get lucky and others get little to no improvement in the amount of bleeding. There's no way to know if it will work for you until you speak to your doctor and try a few of the options.
Depends on the type and your body. Some people have had the Mirena stop their periods while others don't. Same goes for the Depo Shot. The pill can be taken continuously to avoid periods (under a doctor's direction and supervision, of course).