it is 14 clicks full front to full back and side to side. so 7 center it out.
The majority of your sound should appear as coming from the dash. Think of the dash as the "stage". Rear speakers should not be heard at all. they are just rear fill and to give some noise for anyone in the rear.
I admit my system sounds much better for front passengers then it does the rear. Because I dont care about them, i care about me.
And the bass, mid, trevle adjustments are what they are. Adjust to taste. Music is all recorded all over the place and it is hard to get a one setting too fit everything. The best thing to do, is when you design a new system, make sure you have a volume control knob for your sub woofers.
Mids and highs are pretty consistent, but bass is recorded at way different levels, and the volume you listen to it changes that as well.