Where does the power come from? Do I have to buy that separate or will this work right out the box?

Updated: November 10, 2015
APC Paper and Rock come with a 13.5W, 12V/1.5A power adaptor and APC 8750 comes with a 13.5W, 9V/1.5A power adaptor (When purchased through the apc.io website). Just plug it in and the system runs. (APC Rock and APC Paper ship with standard US and European head adaptors.)