Next: the 4 possibilities for sending the signal from:
pre equ : normally used on recording feeds to avoid to be limited on the mix session by the equ that being used live. signal is picked after pre amp and low-cut.
post equ : signal is picked after pre amp, low cut and equ. which is a good pick up point for wedge mixes.
Pre fader: you have all elements of the channel processing including pre amp,low-cut, equ and gate and compressor, but being independent from the the level setting of the fader.
Post fader: all elements as on pre fader plus being dependent from the level setting of the fader.
classic example would be -CD playback track you send to stage monitors- you want the music to fade-out in your wedges same way as you fade-out in the main speaker.