I agree completely! Start with the colon. My experience with Oxypowder has been totally positive. Much gentler than the Cascara Sagrada.
All of your other cleanses will basically dump their trash into the colon and it needs to exit as soon as possible.
If you are fighting candida, you should look into an anti-candida diet, since candida is so closely tied to diet. For any cleanse it is good to avoid foods that tax the system such as fried food, processed food, white Sugar and flour, dairy products.
Go slow and do what is comfortable. Take a practical instead of fanatical approach. Read CureZone a lot. The people here have lots of tips to make these cleanses more effective and comfortable. There is no one-size-fits-all cleanse. If something isn't working or is making you uncomfortable find another approach to accomplish the same thing.