Deploying code to multiple front end servers
You should probably look into Aegir, which is by far the most flexible and powerful Drupal site management/deployment system. It is able to manage 'platforms' that span acros multiple web heads, or 'clusters', as well as a variety of other configurations.

I'd suggest having a read through of their community documentation which is generally pretty good, as well as reading through mig5's excellent overview and introductory article and some of his other articles like this one.

You can also get good support in the #aegir IRC channel.

It'll be a bit of a workflow change, which can definitely take some time to get your head around, but once you're there you won't look back.