You've got a lot of questions in your post that would be difficult to answer all at once. Generally speaking, every ailment whether it's constipation, acne, allergies or cancer, is caused by toxicity in the body. Obviously diet, lifestyle choices and environment are the main contributers to toxins and these are the things that need to change.
I suggest you read through http://www.108pages.com to get a good understanding of how to cleanse the body and move on to a lifestyle that will keep you disease free for many long years. That website is a compilation of MH's writings and contains a wealth of information and a great pdf booklet called 108 pages which outlines a specific program for cleansing and healing. For any of MH's supplements, you can order them from MH himself if you email him, or http://www.restorebody.com also sells them.