So innocent until proven guilty according to the law is something that should be discarded when it is deemed expedient to do so? Free, open and public trials, the use of juries and access to legal representation are mere frippery? Oh dear.
For US citizens no. For enemy combatants yes.

Watchman mostly all youve listed is allegations and most of them by the detainees themselves. The next part of your post indicates that the US indeed is looking into these allegations. There is no doubt that some prisoners have been abused. But when proof of this is shown those responsible are punished. Try that In Cuba. There they probably get rewarded for coming up with better means of torture.