"I don't think the US has ever held the principle that a fair trial is necessary for justice to be served."
Trial before a jury for all crimes is part of the US Constitution (Article 3, Section 2).
"I don't think the US holds very deeply the belief that a suspect is innocent until proved guilty."
From WikiPedia - "Although the Constitution of the United States does not cite it explicitly, presumption of innocence is widely held to follow from the 5th, 6th, and 14th amendments. See also Coffin v. United States and In re Winship."
"I think the US really does believe that the end justifies the means."
Well the above points are it's principles, but as we've agreed before few countries have managed to live up to their principles, but as I've said before that does not excuse us from trying.
"I don't think anyone but the most blindly optimistic terrorist or blindly optimistic commentator sees anyone winning here."
I think that terrorists will feel a sense of victory if they manage to drag the west down and get it to sell out its principles once they going gets tough, awkward or just too expensive.
The effects of apparently showing troubled regions of the world that it's OK to just kill and ignore justice should not be underestimated.