QDBus is an easier way to interact with DBus then using dbus-send. There is also a GUI qdbusviewer that might help finding and executing stuff. But qdbus and grep seem to be a bit better at that for me.
Executing qdbus will show all services that you can talk to via dbus. Given a servicename it will print possible paths and sub-paths. And when a path is also appended then it will print out methods and signals which can be called or registered to. The output will include the names and types of parameters and the return-type.