Here is a link to a collection of links on "How to do everything:
http://www.greenbuildingadvisor.com/...-do-everything
Under "insulation" there is one:
http://www.greenbuildingadvisor.com/...ed-crawl-space
In general, vented crawl spaces don't work as well as unvented ones, as they admit outdoor moisture all the time, notably in summer. This creates musty smell and mold. A lot of what you decide will depend on how you want to use the structure now and in the future.