Help fine turning my speakers

Greetings all,

This is the gear I purchased yesterday (2nd hand) : ONKYO 706 front B&W 303 center B&W HTM62 sub and surround are from this set : http://www.canadahifi.com/review74.php

1) I am a total noob at this. I was wondering if someone could assist me in the configuration process of the speakers (Bass,treble etc`)

2) There's a rotating knob on the subwoofer for crossover... What does it mean what should I set it to ?

3) on the receiver, it asks me for the impedence level of the speakers (lets me choose either 4 or 6) what should I choose ?

Thank you so much for your help guys. Really appreciate it.

Paul.