ebuild rpm intended to work?

[Peter Littmann]

Hello,
the ebuild man-page states the is a parameter rpm like package.
Is this intended to work correctly and I did something wrong or is it alpha-state?

Is there a way to generally build instead of emerging ?
I wish to have something like:

1. emerge rsync
2. ebuild foobar with a debug-log
3. backup the existing package files
4. uninstall the existing package with debug-log
5. install the already builded new package with debug-log

Will grp-install extended to all packages?
I have only a Duron 600 and its very long to build big packages.
I will be happy if I can get all gentoo-packages after one month of release and perhaps for the i586 or i686 arch only but there should be something like that.

Thanks
Peter