2. Comfortably warm. 103 degrees F (39.5 C) at preparation time.
3. I believe it's helpful to take a salt solution cleansing enema just before the coffee enema to help empty the rectum and sigmoid section of the lower colon. So afterwards when you eliminate the coffee enema, there might not be that much visible waste in the return.
But that's OK. You will be eliminating toxins and cleansing your liver, and that is a primary objective of the coffee enema.
4. You'll probably feel better afterwards, and possibly experience an enhanced sense of well being. It's interesting that coffee enemas seem to have different effects on different people. Although it seems counter intuitive, some people report that it helps them sleep more soundly.