Ganging eyes together
 

Is there any way to gang the eyes together, so that when I turn one eye, it automagically turns the other one?

Try using a set driven key, should do the job for you

u could also use locators with aim constraints
set up one for each eye and one master
master controls two at once but the other two can control each eye individualy
i prefer this but set driven is good but this way allows to either move both at once or each eye by itself