Can I use my iPad as a Virtual CD Deck
Let me see if I understand your concerns. You want an app with a single deck interface that takes up the entire screen, but all the DJ apps out there all use a split-screen dual-deck interface with no single deck option. Is that right?

How about this? It's the only DJ app with a single deck interface I can find so far. Got cue points, loops, effect, the whole shebang.

Mixmo-DJ/Pro

Homepage: http://www.mixmodj.com/

App Store links:


http://itunes.apple.com/us/app/mixmo-dj/id483351955
http://itunes.apple.com/us/app/mixmo-dj-pro/id461366285


Youtube Videos:


http://www.youtube.com/watch?v=wGeyVmkmdTE   
http://www.youtube.com/watch?v=bvhHybAfJ9M


Here's a review from a trust source, Digital DJ Tips:

http://www.digitaldjtips.com/2011/12/review-mixmodj-for-ipad-iphone-ipod-touch/

IK Multimedia's DJ Rig also has a single deck interface but it's for iPhone, so it might not look great on iPad but it still does what you want.. 


http://www.ikmultimedia.com/products/djrigiphone/
http://itunes.apple.com/app/dj-rig/id478831717
http://www.youtube.com/watch?v=P3QhZuHbAUY