First of all, thank you for the thoughtful response; I imagine we would have to converse at length to full establish what we agree on, but anyway the real value is in the process. I by no-means identify as a "libertarian", but I am familiar with some of the principles and give them consideration when pondering political issues.
>Libertarians clearly want less power concentrated at a central level
The phrase "less power" is a little vague; to be precise, libertarians want the government to enforce the rights of the citizens, and to otherwise leave them alone. The population does this by collectively granting authority to the government to deal out force legally; the only exception, for the most part, is an individual using force in self-defence. This is the fundamental principle, I believe, on which libertarians base their thinking.
>I think it would be a fair statement that libertarians favor a strong family unit
Absolutely. Though, at the same time, I would wager than purists would not support government legislation that specifically favours the traditional family unit, tax-breaks etc.
>Households run in ways that are almost entirely communist. So why should this non-profit collaboration stop at the front door?
In order for a society to even attempt to be unified, we must first agreed on a set of axioms, shared-truths. We may take for granted that the bond an individual has with their own kin is stronger than that with others. While we can imagine an entirely communistic network where one's personal wealth is equally shared amongst all, it practically cannot work because humans are simply not built that way. There is enough historical data to suggest that it cannot be done. It is morally untenable because it relies on forcefully compelling people to share their resources, where it is given voluntarily in a healthy family setting.
Furthermore, it is debatable wether or not libertarians recuse themselves from their responsibility to be a force for good in the world, and to be charitable; they merely ask to not be forcefully compelled to do so, as this violates the non-aggression principle. The success of the libertarian approach to charity hinges on lessened taxation and regulation creating an environment of unparalleled prosperity and abundance, in which communities will humanely seek to better the world around them.
I think my above points about the governments role in dealing out force legally, which addresses much of the rest of your post. Empowering local and state government is certainly and immediate goal of the libertarian movement.