I want to get traktor pro and am trying to find the best midi set-up that is within my price range. I am quite new to this sort of thing and dont really know jack shit abotu soundcards.

I have a DN-S1500 mixer and want to continue to use that. I am thinking about getting 2 xone:1d's, and a soundcard (thinking the m-audio fast track pro)

Is this an adequate set-up?
Will that sound card allow me to run 4 decks to my mixer?
Is there anything else I will need to buy to make everything work properly?

I tried googling this stuff but am still sketchy as to how the whole soundcard stuff works.

Thanks