CI is Jenkins, which uses the Docker plugin for creating slaves on-the-fly. The plugin has it's share of problems, so I don't use it to build the images itself - I do this using a generalized bash script, which also pushes it to our private repo.

For automatically updating the load-balancer, check out docker-gen (https://github.com/jwilder/docker-gen). I hacked together setup that detects the latest version and points to this-one when a container comes up or goes down. It assumes a lot of things specific to my setup though (versioning of the containers, env vars, ...)