Bluetooth Playback Controls For iTunes On Echo, Google Music On Echo & Other Alexa Devices

Post Updated 10/28/18 - It's a very common question among Echo owners and those considering the purchase: how do I get Alexa to play the music I have in iTunes / Google Music? As of this writing (on 10/28/18) Alexa cannot link directly to either of those services, but she can pair to a device that does link directly to them via Bluetooth, and that will get you some playback functionality.  ...