4 nine-volt batteries in a series-parallel setup to deliver 18V at twice the current.
It is a bad idea to connect batteries in parallel because they discharge / charge each other. Better to isolate them with a diode.
Yes batteries run down quickly with motors a mains power supply is a much better option.
As to the display. You need a trigger to synchronize the display on every rotation. When you see that you just flash the LEDs in the pattern you want.
Like my simple project here:-
