RHEL/CentOS Repository clues

[vodhner at cox.net]

This is a request for cultural enlightenment.

At work, I am doing some development on CentOS.  I
chose that because it is close to Red Hat Enterprise
Linux (RHEL), and RHEL is what we use on all our
production Linux boxes.  Also, I did not want to be
out on the bleeding edge since this is being targeted
at production.

I have tried to use CentOS repositories, but often
have not found the item I was looking for.  So I have
pulled in a few other repos, in a somewhat disorganized
manner.  I have CentOS-Base, dag and MOKs.

PHP came in at 4.3.9-3, and I can't find a php-mysql
that will build against it.  (I was just instructed
to look into --nodeps, --force and -e which might
solve that problem.)  But really, for security reasons
etc., I should be using php5, right?  And with this
repo list, "yum install postgresql" came up empty.

I'm obviously not "connected" yet.

So, could someone please tutor me on the methods for
setting up the repo lists so that all the major
mainstream packages will be available in the
RHEL/CentOS type environment?  Does it make sense to
add Fedora repos as a last resort?  How do I arrange
that the less stable choices will be used only after
trying the more stable?

Thanks in advance,

Vic