data sync 2 + sites

Hi all,

I have a site - ecommerce site but want to have some redundancy built in so that if server1 goes offline server2 in another DC kicks in (and maybe even have a server 3)

I was thinking of this:

Master-Slave type replicated between 2 cpanel accounts for DB (orders / forum posts etc)
600 TTL on DNS to allow for fast DNS update

How do you usually set this up? Any way to automate the DNS change over using 3rd party services?

I have IMAP accounts aswell - will moving DNS to server 2 screw my imap setup or if I keep everything synced (/home/user/mail dir) will I be good in that respect?