depends mate, will add another 90 or so effects for you to use and its fucking good fun controlling them with touch!!!.. It's a possibilty for auxillery mate, first i've heard of it tbh with you, whos on the line up?
Depending on the mixer mate. Generally speaking its just a master effects unit. But on my old vestax mixer you can turn the input of the kaoss pad up and down for each channel. But its still good fun playing around with it just over the master.. Great for nice harmonic intro's and stuff i find!