Creating a redundant server and VCS

Hi,

I'm planning to create a redundant server with following services, so
that in case one server fails, my another server can serve, and also
share load with other server:

* ISC dhcpd
* BIND
* Postfix
* NFS4
* MySQL
* Apache httpd 2.2
* Puppet
* OpenLDAP
* Subversion (or any other VCS (version control system), currently not
running any)

I've never done such thing in past, so can somebody tell me what
solutions (FOSS) are available ?

Is it possible to create a Pentium 4 (or Pentium D or Core 2 Duo)
based redunant server(s) for a Xeon based server ?

I'm not running any SAN or NAS box, so I want storage to reside on
redunant servers and also kept in sync. So, is clustering filesystems
e.g. GFS, recommended for such application ?

I'm not planning to run any compute cluster.

I'm planning to build this with Debian "Etch" or CentOS 5 with SELinux
enabled in enforcing mode. All my clients are running Fedora 7
(SELinux in enforcing mode).

I'm also considering installing a VCS for collaborative editing of
documents (not source code) by users to avoid having redundant,
sometimes out-of-sync copies of the same documents. So is running a
VCS for such recommended.

Thanks in advance
Ashish Shukla