Wow, it IS complicated (I would not have been able to handle last night!). But notice that it is not that the 5th, 8th and 14th amendment protections are extended to terrorists, only that those amendments are referred to, to define cruel and unusual and inhumane treatment. The lack of Miranda warnings is not cruel and unusual. Sure, SCOTUS is given license to eviscerate any interrogation worth anything in war given the mess of the text, but I am quite confident it will not. It is more likely to say, that cruel and unusual is a function of context, and in the context of war, rough interrogation methods are not cruel and unusual, they are normal.
Yes, the bill poses a risk, but a rather remote one, is my first cut at it. Relax, and be happy.