Database and Server mirroring for security / redundancy

[docholiday]

We are going to be building a large-scale website with a massive MySQL backend, served up by PHP. We are concerned about 3 things: server death, a fire at the facility, and hacking.

Basically, we know that we can do load-balancing across multiple servers using RAID but is there a serious lagtime assocaited with grabbing a remote database at another server facility, for fail-safe operation if something happens to one server or another for any reason?

More specifically, we want to have the same dataset mirrored on at least 3 database sets on 3 different servers that are always updated and can talk to each other in the event one goes down, as an airplane engine can pick up the other one's extra load should the second fail.