Karl Schroeder, I'm white and male but not Anglo, and I was born and raised in Mississippi. Believe me when I say that the United States does have a class system, even if it's not acknowledged or given the benefit of official sanction.
And, being that I am from Mississippi, I have an easy off-hand answer for your Question #3: why, the Civil War, of course! Granted that many Southerners these days have no particular interest in history, even their own; granted that, of those who do, most have been so thoroughly taught the Northern perspective on those events that they aren't even aware there is any other perspective -- which, if we accept the axiom that the winners write the history books, is quite true. But so-called "Lost Cause" literature, particularly that of Admiral Semmes, can nonetheless be illuminating, and you don't need to be a Confederate revanchist to recognize that there truly were two sides, two political philosophies and two sets of common interests, at work in the causes of that conflict, and that the South's "peculiar institution" had much, much less to do with any of them than is commonly believed -- and commonly promulgated by the victors' descendants -- today.
If you're interested in the Confederate perspective on the Civil War and its causes, you could do much worse than to read Memoirs of Service Afloat, During the War Between the States, by Raphael Semmes, Esquire, late Admiral of the Confederate States Navy. If you're not interested in the details of his cruise in command of CSS Sumter, you needn't continue past the first dozen or so chapters, in which he provides a succinct and thorough description of the events leading up to the war, from a perspective which does a great deal to complicate the supposedly truthful official line promulgated today.
And if you don't think that's a valuable thing, consider your own declaration, in the post above, anent world-building -- "no facet of the culture would be simple". Presumably (and judging especially by your side-snark at Star Trek with which I fervently agree) you find complexity in world-building a necessity because, in order to produce a credible world for your readers, your efforts must reflect the complexity apparent in the real world, by which all fiction is inspired. This being the case, are you really sure you wish to place all your faith in the exceedingly simple official line with regard to the Confederacy and the Civil War?
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