Reply to Audio8, Ableton & VXT help

Today i just went and purchased some KRK VXT4's. I have connected it through my Audio 8 interface via output 1/2 into the KRK's and USB into my iMac.

I have managed to get the control for the volume through Ableton. But how can i use it so i listen to my itunes music through my VXTs and internet stuff like dancetrippin? Also is there shortcut keys in Ableton for volume control, iv either misplaced my manual or left it at my mates studio..

Thanks.

P.S, Feel kinda dumb asking this..