1) "pretty large" tends to mean the same thing as "fundamental", "general", "widely binding" -- at least in my experience. E.g., "Godel's Theorem was a pretty large rejection of the Russell program."

And no, I'm not defending MacIntyre. All I'm trying to demonstrate is that his arguments against emotivism are worthy enough for emotivists to learn.

2) No. You've never heard someone say, "I may not like it, but it's still good?" For example, there are people who are personally dislike gay marriage, but support it anyway because they feel it is good.

3) Defining "moral approval" as "when people express approval using moral language" says nothing about what the term "moral" means, and that's something any ethical system really ought to get to eventually.

4) Yes: deontological systems don't give one whit about the syntax of a statement; if your 'intention' was bad, your speech act was still bad. Utilitarianism also is more concerned with the actual weal or woe caused by a sentence, not its syntatic form.

And I'm done. If you want to learn more about MacIntyre, read the damn book. I'm a mathematician, not a philosopher.