3) Which specific RPM versions should we use? In my personal experience...
Should we upgrade to rpm-4.2.x on RH7.x, RH8 and RH9, or use the above mentioned versions?
IMO, my preference is that rpm version used should be standardized across *all* supported platforms, ie, use the same version, rpm-4.2.x, for all and be done with it. I believe this will make the building and testing of packages, especially rpm-releated ones (like apt, yum, etc...), more consistent.
-- Rex