Was not really sure where to post this as i have lots of problems.

i have 3 cdj 200 nexus 2 and a djm nexus 900 2. I have connected it all together with usb cables to pc and i have used also  connected the audio cables and back of cdj to mixer (not sure if i need to do this ?) also i have connected eithernet cables from mixer and cdjs to tp - link switch. also connected pc to tp link switch as well. Here is the issues A i dont think i have set it up correct 

B i want to use rekordbox dj on pc

c i also want to go live but when i select the djm 900 as soundcard for live i then cant use rekordbox dj as it wants to use the djm 900 as a soundcard there as well. 

any help would be amazing