There’s no one-size fits all answer, just like there is no one-size fits all controller.
Each venue is going to be different, but can easily be solved before your confirm your booking.
Ask:
1.) How much space for gear is there or can you make available to me?
2.) Mind if I bring my controller?
Now, in terms of going from controller to main sound system, that’s easy, your line out goes to one of the channels of the club mixer. Don’t touch that volume fader for that channel while playing, and use your own mixer. If the mixer has more channels than CDJs setup, then you don’t even have to disrupt anything (just use a free line-in)
In terms of meshing with other DJs, anyone using an audio interface with pass-thru (like NI’s Traktor Audio) allows you to hook up through them without having to replug wires between sets. Chances are though, if you’re using a controller, you will never need more than 1 channel free in the club setup.
.
