Well, I don't think there is (and will be) something like an "official SDK/KDK".
So programming for KT is always "hacking"
My goal is not so different that yours - I want to extend existing functionality, you want to write something completely new...
So I have to find out how the existing functionality is implemented and try to find a way to either use and combine other functionality (e.g. by writing shell scripts and calling the built in daemons) or to extend or reimplement existing Java classes.
Therefore I also want to know how I can use and compile the existing libraries together with my own code and put things together...