Did Rommel really participate in the plot to kill Hitler? Hitler sure thought so. He had his favorite general poisoned; about that there is no question.
Did Rommel know Hitler before the war? Not sure when they became acquainted but Rommel ran AH's bodyguard unit for a while, then became one of Hitler's favorite generals when he helped sweep the British to Dunkirk in 1940.
Was Rommel aware of and morally responsible for the Holocaust? A recent award winning Rommel biography cites one scene I wish they could have included in this film: Rommel around 1941 advised Hitler that he was concerned by Allied carping on German anti-semitism. "Why don't we put some Jews into prominent leadership positions and shut them up?" Rommel suggested. Hitler told Rommel to stick to military matters and, after the general exited the room, told associates: "That fellow has absolutely no understanding of what we are trying to accomplish."
The movie does generally succeed in portraying the theme of a soldier so single-mindedly focused on the professional technique of his job that he only slowly awakens to the moral horror and self-destructiveness of the leader he serves.
The Churchill quote used at the film's ending is meant to address (and answer) the questions about whether it is morally proper to make a film that glorifies a Nazi general. If Churchill could say such magnanimous things about him...and it's an accurate quote...then so could Hollywood.
(Interesting historical note: British film audiences in the early 1950s were not in such a generous mood. The studio quickly churned out the much-inferior "Desert Rats" film, featuring Mason as a more-villainous Rommel, to mollify outraged critics.)
Where did the quote come from that is spoken in this film by von Reunstadt: "Victory has a thousand fathers, but defeat is an orphan"? Yes, JFK used it, famously, after the Bay of Pigs fiasco. Many newsmen of the time mistakenly credited the president with originating it, but JFK didn't claim credit for it. The line has since been traced back to some Italian count in the 1500s. His name was Ciano or something like that. But JFK was a big movie fan and, my guess is, probably learned this aphorism from "The Desert Fox" a decade before using it in his famous post-Bay of Pigs press conference!