Devils, Demons, Fallen Angels or Demonic Kings?

Robin Killen asked me lots of good questions and I suggested that we share these insights on the air.  What is the difference between devils, demons, fallen angels and demonic kings?  What are the principalities, powers and rulers of wickedness in high places in Ephesians 6:12?  Why did Jesus commission us to cast out demons and to minister healing?  How do we prepare ourselves to cast out demons? or to come against demonic kings? What is the courtroom of Heaven?  How do angels do warfare for us?  Hasn't the King of Kings already won the war?