Earlier quoted context omitted.
No, you cannot. Evidence derived from facts learned from torture is also excludable.
Sure, you can. It all depends on who gets to define "torture." If they can find a judge who believes the iron maiden isn't torture while the anal pear is, then guess what... the government will use the iron maiden. Even if they can't find such a pliable jurist, they'll have no problem getting a John Yoo to write an executive memo that justifies whatever they want to do to you, and let the courts sort it out later. Th…
The memos didn't provide de iure indemnity. There is no constitutional basis, in fact the proposition that a memo can supersede the Constitution is idiotic on its face.
The failure is the de facto doctrine of absolute executive immunity. It has two prongs: 1. "When the president does it, that means that it is not illegal." 2. When the perpetrator follows president's orders, also not illegal.
Nevertheless, since there is no legal basis, there is nothing preventing the next government from prosecuting them.