"A few crossfade mix effects such as Break, Backspin"
What is a break effect?
Anyway, I play vinyl and I really think backspin as an effect button or smth is totally unneccessary. As far as i know you can do backspins on CD-s and MIDI-controllers as well. Don't want to be rude but it sounds to me like a "scratch" effect or smth

, something a DJ should do him/herself and not effects doing the real work for him/her.
But delay and echo are my votes.
BTW Cross already kind of has "loop roll", you can do it with looping quite well I think.
I just wouldn't like effects that are duplicating some basic DJ techniques. Only things you can't do already should be added IMO.