package management and administration is a great start to explaining the differwnces, but what I would really like to see is a low level explanation of the differences. To what extent does BSD follow the "everything is a file" philosophy that linux does. Where is information about devices and processes to be found?

coming from a Gentoo background, where portage is based on the bsdports system, package management is not all that foreign in BSD. But when it comes time to tweak things, I start missing my sysfs and procfs, mostly throug ignorance of how BSD does such things.