In traditional qigongs, it’s referred to the chi at the "Central Palace". Actually it’s the chi at the middle chi center. It’s closely involved in the chi of the internal organs while chi at the lower (navel) center is mainly the body chi.

Well, if you imagine your abdomen were spacious void, you may continue to rotate infinitely big circles in your mind while you hands move in endless arcs. This is because your palm center never leaves the skin of the concerned area but your hands push and press the muscles move over the internal organs.

Non-qigong practitioners don’t have such experience. After considerable practice, the practitioner’s abdomen tendons and muscles will become hard, full and round, the cavity of the of the abdominal mid-line will disappear, it’s called "risen tendon membranes" in traditional qigongs.

It needs daily practice for Level One practitioners. Some movements and postures of Body Mind Form and Five One Form also have similar benefits.

Generally speaking, No. It the beginning of the practice, it’s common to experience belching, gurgling of the intestines and farting. Try to hold up the perineum all the time.

If you read Chinese, you are fortunate enough to learn all of the arts even if you can't go to the Center. Otherwise, translations are important.

Yes, I’m pretty sure it is. It’s also the same definition in the Closing Posture of Three Centers Merge Standing Form and Body Mind Form.

Actually, in the similar movements of Zhineng Qigong, the palms (sometimes the fingers) are taken as the "hands" of the "clock", the abdomen (some other parts of the body in other cases) is regarded as the "clock base", clockwise or counterclockwise is referred to the way how your hands move in the eyes of other people facing you, not the way you point and rotate your palms or fingers at other people.