Reply to Question for a future controller for Traktor Help

Hi all I got a question for the guru here,
I have a MBP mid 2010 and evolution uc33 and traktor, I would like to buy an xp 5 because of the jog wheel, but I got few questions.
First can I use one xp 5 to controll both decks?

Do I need another sound card to be able to cueing with headphones or can I use the sound card from xp 5 as master and the PC one as cue Chanel ?

Thanks all for your help