e) Some of the perl stuff which is needed (and thus taken from perl-CPAN) is also available on base/update/dag/dries in RPM form. These are obviously preferred, so it would be nice if as many as possible perl packets which will later be needed could be installed beforehand (still working on this part and minimizing packages take from perl-CPAN, is there an auto perl-CPAN to rpm tool?)
Yes. It is.
Progam is called "cpanflute2" and perl module is RPM-Specfile, I use version 1.17 and it builds perfectly on CentOS4.
Usage is simple:
cpanflute2 MODULE.tar.gz
creates perl-MODULE.src.rpm and the rest is obvious.