To act as a proper firewall for the network you will have it placed between your switch/router and Internet connection. Using it as a "node" is questionable at best. You should use a dedicated distro like Smoothwall . There is documentation there that can help you with the setup.
What do you want linux to take over? I like having choice. I use Mac, Windows, and Linux. I agree that Linux needs more games but a Linux based console is not the answer. Modern development tools are aiding in the creation of cross platform apps. I use Blender( An open source, free 3d...