Re: technical word questions....
I believe what you mean by a moving fader is a motorized fader which is basiclly a volume for a particular channel
mixer channels:a mixer is a unit that you plug any number of inputs (ie;mic,guitar,bass,piano etc...)channel 1 may have guitar channel 2 bass and so on.Then you ajust the "faders" for each channel so you can hear all the instruments clearly.
efx sends returns are an efx loop like on a lot of giutar amps.So if u had a delay pedal u would plug the output into the send and then the return from the amp would go to the input and yer giutar plugs into the front of the amp.