Phil,
Well written and thought provoking. Reading this, I was reminded of a Douglas Adams essay/speech abut Balinese rice farmers and the way their religion is highly suitable to growing rice. The gods that they cite as reasons for this or that aren't necessarily real and some of the practices may actually be useless, but the end product is a very successful harvest. You might ask a rice farmer why he decided to plant this plant here. His answer could involve some custom that if the moon does this and the chickens do that, I need to put a plant here. That'...
Phil,
If you are looking for others' thoughts that may be able to tie your post together, you might want to read the Douglas Adams Artificial god that I cite here: http://lesswrong.com/lw/18b/reason_as_memetic_immune_disorder/14az