Looking for a user-friendly 4-out interface for beginner DJ.

[Nightwriter]

Also make sure it is USB powered and no need for an external power source. Don't want too many cables.

[blacktiger]

On the contrary--Live is excellent for DJing. Ask Deadmau5. I actually was referred to it as a beginner because of its budget-friendly price and that I didn't have to go and get a CDJ or Technics turntables. I'm a serious hobbyist, but I'm just starting out.

I use the Launchpad as my mixer, as it has a mixer mode on it. At times I drop one track after another, but most of the time beats are layered on top of each other as I fade out from one song as I fade into another.

I primarily DJ house, some electro, dubstep, drum-n-bass, grime and bashment.

The Audio 2 sounds like the plan...and a fantastic price!

Yeah, thumbs up on Live for DJing. I'm a jazz guitarist/upright bassist who's also been DJing since the vinyl (and, sadly, cassette!) days. If you plan on playing out a lot, you might consider an integrated controller/interface like the Hercules DJ Console, which is what I use. I also just last year got the Hercules MK4. Even though it's on the low end, it's stood on its own at large venues - such as weddings when the rest of the band was on break.
Either way you only need to worry about your computer, headphones, and audio interface/controller. For me that's three main things to remember to bring to the gig. Then there are the backups (extra HD, extra cables and backup interface, headphones, etc.). The reason I like the MK4 is because it's an ultra-portable, integrated unit - and it still has the higher end A/D converters. People bag on it for various reasons, but as long as you don't beat it up it's reliable.
Anyhow, whatever you choose nowadays you can't go wrong. It sure beats finding the cue point on some cassette! (Shakes cane)