Pengutronix OSELAS (
http://www.pengutronix.de/oselas/too.../index_en.html) is the most polished cross-compiler build system I've found.
The Nokia N810 is remarkably similar to the Kindle in terms of base hardware and a very convenient bootstrapping tool.
qemu-arm's SCSI drivers are very cranky.
http://fedoraproject.org/wiki/Archit.../ARM/HowToQemu has a decent writeup of how to do an NFS-rooted ARM-linux system, but
http://people.ubuntu.com/~ogra/arm/qemu/ has the ubuntu images I found useful.
The Kindle's kernel has baked in NFS and Ext3 drivers.