What, me, an anarchist?

The original title of this post was a call for responses from my Anarchist readers (see questions below).
Only a few weeks ago I thought Libertarian’s were full of crap. I only knew of “Libertarians” as essentially pro-choice Republicans. Since then I’ve had some interesting conversations on Facebook, and I’ve done some reading. A solid handful of Facebook friends have given their perspectives, informing my new ideas. Reading the anarchism sites (see links below), I keep thinking I’m very close to being an Anarchist, or, a Libertarian Socialist.
Big problem, though. I can’t entirely support one of the basic premises of anarchism: eschewing or even flat out rejecting all hierarchy. This is the foundation as I understand it. I find this not only impractical, but can’t wrap my brain around any community that doesn’t have some sort of administrative body to, yes, administer as necessary. And, within administration, there (it seems to me) must be leadership.
In my experience, groups of people typically have only a very small minority of members/participants who understand what kind of administrative tasks are required to make even the most egalitarian system successful. From what I’ve read so far, anarchism doesn’t address the realities of running any kind of organization (large or small) but simply says, “we won’t know until it’s happening.” Quoting Howard Zinn, “You cannot have self-sufficient little collectives, because these collectives have different resources available to them. This is something anarchist theory has not worked out and maybe cannot possibly work out in advance, because it would have to work itself out in practice.”
I’m also lately considering and reconsidering what has been a passion of mine for several years now. This passion is one that leads me towards considering anarchism. Since I read Barbara Kingsolver’s Animal, Vegetable, Miracle, especially and before that when we joined our CSA in 2003: Eat local, buy local, etc. It has all made sense to me where it matters most, in my heart. Logic played a part, too. Local businesses flourish, the environment takes less of a beating, food is fresher and healthier (and tastier), big box beast companies have less success destroying small farms/small companies, etc. After hearing from the author of this article, though, I’ve been rethinking how I feel about the localvore movement. It totally shook me. I’m in the high 80s or more percentage-wise that I’m going to stay committed to the movement. But, honestly, it freaked me out when I realized how much in common I had with some of the most bizarrely, freakishly isolationist sorts I’ve ever encountered. (See question #3 which touches on similar concerns.) So, on to my questions. I am hopeful some of you may give me some thoughtful answers — even if you just give me some decent links. Thanks in advance!
How would you, an Anarchist, answer the following questions?
1) What constitutes “small” in “small collectives?” At what point do these small collectives become too large and need to be broken apart, or… what happens when they grow?
2) How would resources be shared among the collectives?
3) How is anarchism not isolationist, selfish, and self-serving?
One of the conflicts I’m having with the theory is that, yes, I agree hierarchy often leads to oppression. But, if we have no hierarchy (no government leadership) doesn’t that lead to a “to each their own” mentality? How does the attitude of service find its way into the community if there is no statement of commonly agreed upon values (i.e. the Constitution)? It seems to easy for anarchism to equal = do what feels right for your community however you define it which could very, very easily lead to “and screw the rest of you.”
4) In my view: Fighting for justice requires organization. Organization requires leadership. How does anarchism agree or disagree with these statements?
Thanks, again, for any info you share. I most definitely thought “anarchism = chaos” and never pursued the theory beyond that mistaken association. Of course, I’ll do my own further reading. But I thought perhaps it might be interesting for you to consider answers to these questions. In particular, #3 — if I had put them in order of importance to me, what seems most pressing, most incongruent with what I perceive as the otherwise social-justice oriented socio-political theory. And, once more, thanks for taking the time to share your thoughts.