Is the life of reason and virtue the end in itself? If so, why do some people choose to live lives that are not of reason and virtue- what is their end?

Yes. And right, people who choose to live lives of viciousness and ignorance have the same end, they just radically misunderstand how to get there. The purpose of virtue is good action, a life of which is the happy life. And happiness is an end in itself. No more turtles after that, at least that's what NE X says. You might not like his answer (there's a lot to object to), and you might object to my specific reading, but it's not as if Aristotle just didn't address it.

Oh, I understand the theory he has. I want to shove that diagram in his face, say "Here is an example of three things, each of which is contrary to the other two, existing on a continuum.

He raises that worry himself in Metaphysics Iota 5, with the triad 'equal' 'less' and 'greater'. So if you shoved that in his face, he would probably admit that it's a real puzzle for his view. His explanation in Iota 5 is confusing, but so far as I can tell he would say that apathy is a privation of love and hate alike, and therefore a kind of intermediate:

"The equal, then, is that which is neither great nor small but is naturally fitted to be either great or small; and it is opposed to both as a privative negation (and therefore is also intermediate)....[the equal] is a joint denial of opposites between which there is an intermediate and a certain natural interval."

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I can forgive him for not being able to determine the limit as dT->0.

I think he would have been very interested in the development of calculus, but you're right that this was not in his arsenal. I don't think he really contradicts that though. Much of the argument mid-Physics is centered around the claim that continua cannot be composed of extensionless points. I think he would have accepted the idea that continua can be constructed from an infinity of infinitesimals, since these just have infinitely small extension, not no extension.

We would now contradict Aristotle about the construction of a continuum from extensionless points however, since we can construct the real numbers by Dedekind cuts. But its not clear to me Aristotle would even have found this an unwelcome modification.

Really, if you wanted to freak Aristotle out, you'd just show him that we've traveled past the moon. Or evolution. Or you could just point out that slavery is super, super evil, and not good like he thought.

Perhaps my translation adds to my issues with the work; learning ancient Greek is out of the question for me; is there an English translation that you would recommend?

I don't think it's worth being picky about translations. There's only so much precision to be had in a 2300 year old text, transmitted by a 2000 year long game of telephone. Just remember that Greek temples and statues were painted in garish, silly colors, and Aristotle spoke with a lisp because he wanted to fit in with the Athenians. And that he probably married his slave after his wife died because he loved her, and that he wrote Nichomachean Ethics for his nephew, because he wanted him to become a good man, and that he probably thought he would never be as smart as Plato.