You are supposed to do the salt water flush every day. It should be the first thing in the morning and should be a quart of lukewarm water with 2 teaspoons of Sea Salt . Most people just use Sea Salt and water. Yes, you will go to the bathroom a lot, be prepared to be near a bathroom for 2 hours after the salt water flush.
You will lose weight, but this is a cleansing fast, it's not meant to be weight loss program. The Master Cleanse should be part of an over all program of eating right and exercising. If you are eating poorly now and continue eating poorly after the master cleanse, you will regain all your weight and potentially more weight because your metabolism will be slowed down by the cleanse.