Interesting question - in part because your notion of meta-ethics is quite different from mine. You want meta-ethics to answer the question "What ought I to value?". That is an important question, but it is not usually understood to be one of the central concerns of metaethics. But since ethics answers the question "Given my values and those of people around me, how ought I to behave?", it does seem that the "What ought I to value?" question is in a kind of meta- relationship.
This is one book that tries to answer the "What should I value?" question. I thought it was pretty good. Philosophy, but not modern analytic philosophy. I don't know that I would call it naturalistic, though. (The cartoon version of its answer to the question: "You should value as little as possible - try to shed your desires.")
Three books on naturalistic ethics that I have read are Gauthier's "Morals by Agreement", Binmore's "Natural Justice", and Nozick's "Anarchy, State, and Utopia". All three are excellent, though the third (and to a lesser degree, the second) focuses on "macro-ethics" issues of what society ought to do, rather than the pure ethical issue of what you ought to do to others. (No one seems to focus on the micro-ethics issue of what you ought to do concerning yourself - that is a bit of a shame.)
Another recent book on naturalistic ethics that I have not read is Sam Harris's "The Moral Landscape". Harris is well known as one of the leaders of the "Gnu atheists", and the book has been much reviewed in the blogosphere. My impression is that it will be a decent read, but will waste time talking about God (i.e. how Harris sees no need for that hypothesis), when what you want is talk about ethics.
The Gauthier and Binsmore books would be considered works on meta-ethics to large extent, but they are not good primers. They present very particular and unusual views. The Irvine and Nozick aren't about meta-ethics hardly at all, the way Anglophone philosophers use the term. The Harris book is about meta-ethics, but like Eliezer, Harris does not have much interest in engaging contemporary meta-ethics, even though he wants to cover all the same ground. (The scholarship virtue is not on prime display, here.)
Miller's An Introduction to Contemporary MetaEthics is one of the few overviews of meta-ethics available, but I for one did not care for it, and I think it will be especially confusing to beginners.
What would be ideal is a book that covers the major schools of thought one at a time, explaining the basic arguments for and against each position, like Lycan's Philosophy of Language: A Contemporary Introduction does for philosophy of language. Alas, I have not yet discovered any such book for meta-ethics.
There are plenty of anthologies on meta-ethics, like Arguing About MetaEthics, but they don't make for good primers.
Popular introductions to ethics like the Rachels and the Singer and even the Gensler focus almost entirely on normative and applied ethics, not meta-ethics.
Major books that cover all the basic questions of meta-ethics are generally written by a single author and come from a very strong and particular point of view, e.g. Smith and Brink.
The best recommendation I can come up with for a primer on meta-ethics is probably Jacobs' Dimensions of Moral Theory, which doesn't go very deep at all, but maybe that's best for a primer anyway.
The problem may be that meta-ethics draws on a huge number of other fields, and so there's little hope of writing a coherent 'introduction' to the subject that doesn't assume large amounts of knowledge about philosophy of language, psychology, epistemology, and so on.
Two final mentions. One of the most important anthologies of original research on naturalistic meta-ethics in the last 20 years is Moral Discourse and Practice. A good introduction to non-realism (specifically, error theory) is the first couple chapters of Joyce, which is pretty readable even for beginners.
In addition to Jacob's book, the best introduction you can get to meta-ethics is probably to read the relevant articles in the Internet Encyclopedia of Philosophy and the Stanford Encyclopedia of Philosophy, for example:
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That said, this entire post may be of little help, because the questions asked in the original post are, for the most part, not meta-ethical questions! (Perplexed noted this, too.)
Good luck!
Update: I re-read parts of Miller's Contemporary Introduction to Meta-Ethics. I like it better now than I did the first time I read it. The early parts are rough, but the chapters that matter the most (on error theory, and on moral naturalism) are good.
I used a blank line after 'SEP' and two spaces at the end of each URL line, yielding this:
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Can anyone recommend a good primer on naturalist metaethics? I've read the Fun Theory Sequence, and found it fascinating, but it only deals with fun. There are also life, death, pain, torture, and possibly other goods & harms to consider. Also, the Fun Theory Sequence tends to focus on macro-metaethics, i.e., what would be best for all of us to do together? I would also like to learn about micro-metaethics, i.e., what should I do with my life, and how should I choose which parts of myself to emphasize, or which parts of myself I will think of as "really me" or "the best part of me?"