[UPGRADING] What gear do I need for what I want to do ?!

Hello all.

I am upgrading all of my DJ gear and I plan on changing my workflow, a lot.
Right now I'm using a Numark Mixdeck with an Akai LPD8.
I'm selling the mixdeck.

What I would like to do is the following:
I would like to use a NI Maschine, Traktor Pro, an external mixer, and a controller for traktor (could be my akai lpd8, or maybe the X1).
I want to be able to control traktor with the controller and the mixer, and use Maschine to drop samples and kicks etc. on the fly in a live set.

Now what I can't figure out is this:
What kind of a mixer do I need ? 2 channel or 4 channel ? (I use strictly 2 decks in Traktor, not more). Does the mixer need to be MIDI compatible ?
Do I need an external soundcard ? (Audio 2,6,10 ?)

As you can see I can not figure out how to hook everything up. I do know that i can use Maschine and Traktor on one laptop simultaneously.

Be creative, have you got any solutions in mind ? Let me know PLEASE.

ps. let's consider that there is no specific budget but of course I wish to have the best value for money.

With kind regards,
dsmit