I don't disagree with all of your descriptions of the "spectrum". But I do disagree with this:

"Most of the notions we have of liberalism start at the center of these curves and extend by small gradient steps in the general direction of the anarchic extreme; most of the notions we have of conservatism start near the center and extend toward the more controlling.

Liberalism, at its extreme, extends toward the TOTAL control of all things economic -- confiscation of all wealth-producing capability until all essentially work for the state, turn in all product, and redistribute it. Conservatism does the opposite, at its extreme presupposing that the market will control inequities.

Your description SEEMS to fit more with the social aspects of society...

...except that, whereas conservatives may tend toward the control of things like abortion, pornography, etc, liberalism will end up controlling all the minutia of life -- from seatbelts to what we eat. After all, when the government takes the responsibility for everyone's life from cradle to grave, it ultimately must see the need to micro-manage it all. For instance, if it pays for health care, then it has a vested interest in making sure that nobody participates in health risk. In that vein, liberalism will end up battling within itself AT LEAST as much as it battles conservatism -- because the unintended consequences of governmental care will forever be in conflict with liberal's natural inclinations toward libertine living.