Why The Great Gatsby requires two readers - and the most intelligent narrator in literature?

Sometimes the Fitzgerald's writing in The Great Gatsby is so fine and evocative (and sometimes so difficult - I have to admit that there are passages where I put a ? in the margin) that I get lost in the writing and miss key elements of the story - and then have to go back and clarify - for ex. I am always confused about the car trip to NYC w/ Gatsby's car and Tom's - who's in which car and when?. There are other times when I'm so involved in the beautifully calibrated plot that I read too fast and just read over some of the fine writing. You have to be two readers at once to truly appreciate and comprehend TGG. But for the moment let's look at another element: the characters. Esp., the character of Gatsby. I was surprised - if you'd have asked me I'd have said that the great reveal about his background comes only at the end, at the funeral, when his rather bedraggled and puzzled father arrives - but in fact about half-way through the book Nick Carroway tells us that his real name was Gatz, that he worked in the Great Lakes fishing industry for a while after high school, became enamored of a yacht he saw at a pier and signed on as crew and learned the ways of the upper crust - leading to his new name, new life, new fortune. People talk about this as a typically American success story - only in America could one completely make over one's life and rise to the aristocracy - yet that's a half-truth, I think. Most who become extremely wealth in the U.S. (particularly in the pre-income tax days) actually boast of their humble origins, with Lincoln perhaps being the model: in literature, think of Silas Lapham, whom I've blogged about recently, as a model. There's something odd about Gatsby's social climbing - and it's peculiar that, if he new image as a bon vivant "Oxford Man" was so important, why did he build his fortune on gambling and bootlegging? I guess that was the opportunity most available to him? The story hinges on his long-held passion for Daisy Buchanan - everything he accomplished was in an attempt to catch her eye and win her back - but it's a strange passion, and we can't help but think he wants her as a trophy, as another purchase, another accomplishment. He is entirely about exteriors - and about European emulation: the stupid fake castle he lives in being the primary symbol. And he's completely self-involved, as are all of the characters Nick meets during the span of his life: they are careless, as Nick says, which is a complicated word: without a care? unable to care for others? for themselves? The ultimate carelessness is car accident, a fatal hit-and-run and all they can think of his protecting one another, and how upset Daisy must be by her killing a pedestrian. Horrible people, all of them, but the novel soars above all of them, so carefully and thoughtfully unspooled for us by tone who may be he most intelligent narrator in literature.