Well, I can make some partly-educated guesses.
Exactly how does hypnosis work?
How is the conscious mind involved?
How is the subconscious mind involved?
Why are some people more susceptible than others to hypnosis?
I don't know how hypnosis works, or why some are more susceptible than others. Susceptibility may be related to past experiences, the person's level of trust in others or paranoia, open-mindedness, level of self-awareness... but those are all just guesses.
Level of consciousness may not be all that useful in understanding hypnosis. You can think of consciousness as a flashlight. We can only attend to a narrow beam of stimuli at any given time; and the rest of it remains unconscious. Some theorists also use a level they call pre-conscious, which would be on the border between conscious and unconscious. I hear there has been some fascinating work done on levels of consciousness, but couldn't tell you more than that.
Hypnosis clearly involves working at an unconscious level; people hypnotized into doing something strange will often not be aware of their behavior. But how the unconscious mind is involved in hypnosis is actually a pretty vague question that I can't answer.
What effect on emotions can hypnosis cause?
What other effects on the mind can hypnosis cause?
What effects on the body, short and long term, can hypnosis cause?
What are some of the more spectacular and well documented cases of hypnotic effects?
I'm sure hypnosis can have a powerful effect on a person's emotional state, but not a long-lasting one. But emotional states are changed easily. The right stimulus can change your emotional state immediately and dramatically.
I have a friend who took a hypnotherapy class, and as I understand it, it's basically used in an attempt to modify behaviors (like changing one's diet for purposes of weight loss). The therapist tries to establish an alliance with the part of the person that wants to change, and enhance that, while suppressing the part that is opposed to it. It evidently works well enough for some people to still be used, but it's obviously no miracle cure.
Some of the more amazing effects that I've heard of are reminiscent of advanced yogic stuff, pointing to ways that the mind and body are connected that seem strange to us. For example, some people who go catatonic may become extremely rigid. I've heard of people being hypnotized so that their arms remained locked straight out, and no matter what, their arms could not be bent. I've heard that it can be a substitute for localized anesthetics, completely disconnecting people from experiencing pain in very specific parts of the body. But I've never really seen such demonstrations of hypnosis, so I can't personally vouch for it.
I do recall one story a professor told me. Oddly enough, this wasn't a psychologist, it was a high school English teacher. He had learned a little about hypnosis as a parlor trick, and was using it on a female volunteer. While you can't make someone do something they would not normally do, you can still trick them: he had her going through her morning routine, and when she got to the shower, she started taking her clothes off. He hadn't intended for that to happen, and he did the gentlemanly thing and stopped her. Such power, I think, is too great for any man to possess.
