read the Qu manual for details
go to setup at bottom button by screen on right
then look for usb on screen and push
then at that screen make your assignments
sorry but I have no idea what the mac needs to make usb work
as to video you need to feed the projector directly from the mac not the Qu
again that is a mac question for them to answer
you can also send sound from the Qu to wherever you want it heard on speakers for both simultaneously on screen and speakers