Reply to How to DJ a live performance with APC40? HELP!

Hey,
I have been producing in ableton for a little bit now and use an s4 and f1 to dj with. Kinda over traktor and not being in "complete" control of my music and really love how the apc40 works.
Now i just wanted to know what i would need to play live.
Sound card/Audio interface?
External hard drive?

Are all of those a must and am i missing anything?

thank you!