Any time you get errors from emerge, try re-syncing (emerge --sync). As much as i love portage, I'll be the first to admit it gets flakey sometimes
after resyncing, try this -
Add the following lines to /etc/make.conf
ccache will reduce the compile time for KDE/Gnome/OOo/Mozilla/<insert big huge app here> by ALOT.
Also look into using the split ebuilds for KDE instead of the meta-package. http://www.gentoo.org/doc/en/kde-config.xml