No problem. Ask away.
1) The same program that commands the skull motion also has a function that sends semi-random commands to the eyes.
2 & 3) The skull is one that was bought, not made. A Christmas gift some years back from my wife. It's from http://audioservocontroller.com/
4) There's a servo for the jaw as well, and I drive that through an audio servo controller that converts the sound volume to jaw movements. Over the years, I've used boards from Cowlacious, a Wee Little Talker board, and starting last Halloween, my own implementation, ChatterPi, that runs on a Raspberry Pi (which provides almost all the features of commercial boards combined and can run on a dirt-cheap Raspberry Pi Zero. What I need to do for this implementation is just use a wireless mic as input to the audio servo controller. Stay tuned for a demo...