I have four servers. Two are DNS servers with websites, a third has only websites, and an email server. I want to mirror/backup/host the websites on a server so that if one server goes down, I can still have have those websites available.

How do I do that?

I'm not sure if that's possible with a RaQ. RaQ's were designed to be simple servers who were for people who's websites had outgrown paid hosting, but did not have the technical skill to run a full blown server. In order to do what you want to you, you would need a server that can do Redundancy Switching. RaQ's do not do Redundancy Switching.