To be honest, all of the above goes totally over my head.
I plug my bass in, and I play, and a noise like a bass comes out. I twiddle with the mids and play, and a noise like a bass comes out.
I can hear a subtle difference, but I've no idea how you would tailor that to go with what the rest of the band is doing. I just don't hear "frequencies" like some people on here seem to be able to do. I have pretty much everything set on 12 o'clock and I play. I can twiddle for hours but all I do is drive myself mad. Except from the extremes, nothing sounds particularly better or worse, just different, and after a while I lose the will to live, put everything back at 12 o'clock and crack on.