@danielquinn, I already have a Kodi skilll that works very well. I am in the process of updating it to support the common play architecture. I am definitly interested in what you might be developing.
Currently mine supports, music / youtube(music/videos) / movies, these are already working, my next release will include TV-shows and I am also planning the ability to cast any items from the kodi library to a chromecast enabled device.
My original work is here