One thing just to start

"Figure you earn your living from this box"

The key word here being box. Singular. If this 'dynamic web application' was the sole bread winner for my company I would want some sort of fail-over solution. One server, One point of failure. Regards the Mod_Perl requirement, you may want to read Choosing an Operating System and Hardware over at perl.apache.org.

Hope this helps.

Martin