I disagree that any of those three points are unimportant, they're central parts of Harris' argument and they are part of what has to be refuted.

The idea that there has to be a "rightness criterion" (or an "intrinsic" criterion as per the article) is very much what Harris' view questions, and his position has very little to do with hedonism (hedonism is just a partially-intersecting sub-set of what he's talking about).

To violate Hume's distinction, you don't need to say there's a "higher meaning" in fitnessism, you just need to say that a "rightness criterion" can be based on "what is" (how animals actually behave).

It's like this: Hume's distinction, while valid, is (contrary to his belief and popular belief) irrelevant to morality. A reason has to be given why the "ought" of morality cannot be instrumental all the way down (or rather up and down), why morality has to have an "intrinsic" or "absolute" criterion at all.

Essentially, all that's happened is that people formerly thought that moral behaviour had to be mandated or commanded by a God. God is dead, but people from the time of the Enlightenment on still had a vague feeling that there has to be some kind of "ought" that's not instrumental, that grounds morality - as it were, the ghost of a mandate, a mandate-shaped hole at the root of morality.

What Harris is saying (and I agree) is that no mandate or command is required for morality, there is no other kind of "ought" than the instrumental, there just seems to be; and it's the instrumental "ought" that's at work in morality just as it is in, e.g., technology, from the basic level (which everyone agrees on - i.e. science helps with the nitty gritty) to the high level (at the level of the "if" of the "if .. then", where there's doubt, where people think there has to be this other kind of mysterious "ought"). The trick is to see how.