1. No, it is rather due to gas bubbles as a result of taking the colon cleanser.
2. There is natural caffeine in green tea that is bound by bulk. Caffeine is not harmful unless it is isolated and released into the blood without going through the normal digestive process first. Regular black tea is fermented green tea, stripped of bulk that would prevent the sudden release of caffeine into the blood. Guarana has also caffeine in it and it has very healthful effects. There are other foods that have caffeine in them but do no harm to the body as long as they are passing through the digestive tract.
4. The crack reflects years of dehystration in the tissues making up the rektum area of your colon. Topical applications can have only limited and temporary effects. It is a matter of trial and error to find out what creates the best relief. I am not aware of anything better than you are already using.
5. Phsyical toxins are the counterparts of emotional of mental toxins. When they become released as a result of cleansing and circulate they can produce mental experiences of release. Nightmares release tension, stress, and even pastlife trauma. The colon is the seat of the subconsciuous and, therefore, a storage place of subconscious impressions.