I work as a DJ on the side. If you want to use MC for DJing (which is not the "normal" thing to do, there is dedicated software that does a better job), then I think you should use zones and the zone overview to just route audio to the appropriate zone. That shows you two playlists, you can drag songs from one to the other, and prelisten on the headphone zone, play on the main zone. Turning MC into a capable DJ software would require a ton of specific UI work, I guess, and it is not what MC does to do in the first place anyway (My humble opinion, please correct me if I'm wrong, Jim)
But again, I recommend a DJ-Software which doesn't require dedicated hardware, which is actually most of them these days. Look into Serato, Traktor or VirtualDJ. They have free trials, and they give you minute control on pitch, timing and mixing. and have waveform analysis, color codes, anything you need. And they don't cost the world either.
I personally use MC to generate my playlists and manage my metadata needs, and Serato DJ for playback. If you DJ even halfway regularily, please consider investing into a cheap controller. You will never want to go back, believe me. It's worth it. Happy to help with that if you wish.