Where to find packages names and versions for RedHat?
The best you can do, as it seems, is to check the FTP directories of the source packages:
Keep in mind that RedHat has the habit of patching software to hell and back, so the version number might not have to much in common with the actual release, especially for the kernel.
For starters: http://distrowatch.com/table.php?distribution=redhat has a list of the important versions, but certainly does not list all package versions.
Apparently Red Hat does have such an online package list for its RHEL distros, but it's only accessible for paying Red Hat customers :-(
Btw. similar question (for CentOS): https://serverfault.com/questions/239205/official-online-rpm-package-browser-search-for-centos