With respect to your question, asking if "waterboarding" is torture is sort of like asking if "sex" is rape. Precisely the same physical actions can, in different contexts constitute radically different acts. A man can have sex with his wife and it can be an act of love. A man can force his wife down onto the bed against her will and it can be the gravely immoral act of rape. In the case of military training, the whole point of subjecting people to waterboarding is to *build them into better and stronger men*: to humanize them. In waterboarding prisoner, the whole point is to terrorize the prisoner, dehumanize him, and break him down into something like a frightened animal. That's part of the double-think involved in justifications for waterboarding and other forms of torture. On the one hand, we are told is "really works" because it has the victim begging in no time. On the other, we're told it's not torture.
There's a whole lot more--go read the whole thing!