The first thing I would look out for is security. Its all very open, and very hackable as well. There are already several npm's for different web auth's Facebook, Twitter, Google, etc. Those or others could be used to layer some defense, and would be good experience for a starter.
There are also many different npm's for making connections(Websockets etc), as well as databases.
I should say I have no idea how the file system would or even need to fit into that, as well as no idea how well Node-Webkit would work for a server.
Also working the packages in with C2's sdk will probably be an issue. In fact I'd wager it would require rewriting some to suit C2.
Then you also have to take into account the third party nature of all that, don't want to step on anybodies toes.