Finding yum equivalents of apt repositories?
Yes you'll need to do this manually. Also take note that some packages go by different names in Debian/Ubuntu vs. CentOS/RHEL/Fedora, so comparing them is going to be tricky.
rpm & apt commands
These sites include nice tables that show particular package management tasks and how to perform them using the corresponding commands on CentOS/RHEL/Fedora and Debian/Ubuntu.
- Comparing Redhat and Debian Package Management
- RPM DPKG Rosetta Stone
These will be helpful when attempting to compare the packages installed on the various systems.
RPM tools for comparing and indexing
Though these tools are RPM specific, they may prove helpful in comparing various RHEL/CentOS/Fedora systems among each other.
- rpmsnap & rpmsnapcmp - A simple set of scripts to compare the contents of RPM databases on different machines, or on the same machine at different times.
- rpmcomp - compare RPMs installed on multiple systems, or compare versus previously recorded list of installed packages
RPM/DEB package tools
These tools are meant for comparing different versions of actual .rpm or .deb files. It's primarily geared towards package maintainers but may be useful if you have any custom .deb or .rpm files whose deltas between them need to be tracked.
- pkgdiff - Package Changes Analyzer (pkgdiff) is a tool for analyzing changes in Linux software packages (RPM, DEB, TAR.GZ, etc). The tool is intended for Linux maintainers who are interested in ensuring compatibility of old and new versions of packages.
Conversion tools
These are tools which can assist in converting packages from one format (.rpm) to the other (.deb) or vice versa. Tools like these are helpful if you have a binary package in say, .deb format, and you either have lost the source or don't want to spend the time rebuilding it. This type of tool can have mixed results but can be helpful in a pinch.
- alien - Alien is a program that converts between the rpm, dpkg, stampede slp, and slackware tgz file formats. If you want to use a package from another distribution than the one you have installed on your system, you can use alien to convert it to your preferred package format and install it.
Yes, it's too variable for there to be an automated way to look it up.
Easiest way to find what package provides what file is to issue a yum whatprovides for instance to figure out what package you have to install to get the setcap command you can issue either a yum whatprovides */setcap or yum whatprovides /usr/sbin/setcap That will help you work around issues where you know what one of the files provided by the package is, but not what it's called on RHEL.
Note: yum will need the repo that provides the package you're looking for in order to find it. This shouldn't be a problem on CentOS since there's a glut of packages available by default.