The answer to the first question is yes, and to the latter two it is no, according to a psychiatrist who is a hypnosis expert. Thus, while the psychological state of hypnosis has its limitations, it can also produce some dramatic—and surprising—changes in the world of the mind, body, and human behavior.
To read more on this provocative subject, especially on the psychiatric conditions that can be helped by hypnosis, see Psychiatric News at http://pn.psychiatryonline.org/content/46/13/10.2.full.
A book about hypnosis is also for sale through American Psychiatric Publishing titled Trance and Treatment: Clinical Uses of Hypnosis, second edition, by Herbert Spiegel, M.D., and David Spiegel, M.D. See http://appi.org/SearchCenter/Pages/default.aspx?k=hypnosis.