Thanks to all who offered answers and insights regarding my questions. But of course answers and insights beget other questions.

Did Hitler have any tangible reason to believe that Japan would declare war on Russia should he do the same vis a vis the United States? In other words was there a memorandum of understanding or somesuch? Or was Hitler merely being hopeful in thinking bold action by him would lead the way?

It seems strange in any case that he would have put such trust in members of a race he must have thought inferior. The better course–and maybe it is easy seeing only in hindsight–would have been for him to simply breathe a sigh of relief that Japan had diverted our attention and in that not insignificant way furthered his designs regardless of any consequence relative to the Soviet Union. (And after all, the Molotov-Ribbentrop pact proved an already sufficient answer for dealing with that front, leading to another question: Why not let sleeping dogs lie? Why attack the Soviets? Or was Hitler constitutionally incapable of trusting in such alliances, especially if he felt he’d already been double-crossed by the Japanese?)

Of course Hitler believed without reservation and managed to convince a whole nation the myth of Aryan supremacy. Even against the countervaling evidence of a Joe Louis or Jesse Owens, that mythology survived. Goes to the power of personality and will to be deceived. But one didn’t have to be especially observant to see Hitler didn’t possess the physical features he touted as supreme. How much self-loathing propelled the man and the myth? It’s interesting to consider even if there isn’t a definitive answer.