First of all, here's what I'm working with....
Axiom Audio M1Ti's (front and rear)
Axiom Audio M1 Zero (centre)
Axiom Audio EP125 sub
Marantz SR5200 receiver
Panasonic DVD (RP52-K or something like that)

I have a ton of questions, I hope someone can help me out, local audio stores and previous internet searches have been foggy at best, and sometimes totally useless.

1. What is the purpose of the phase switch? I flick it and I hear no difference in sound from the sub.

2. What is the suggested setting for the audio/video switch on the sub? If I switch it to video, the bass seems to increase, which leads me to turn the volume on the sub down.

3. I was told that because my speakers are so small that I only need to use 16 gauge speaker wire, do you agree?

4. My receiver allows me to adjust the level of each channel, from -15dB to +15dB. If I set the levels at 0, I have to turn the main volume up from -75dB all the way to +2 to get a decent level of sound. By adjusting the levels up individually, am I providing more power to the channels, therefore creating more headroom and potentially improving sound quality? Or am I turning it up too much and degrading it. Likewise, by having the master volume up so high, am I possibly degrading sound quality?

Your help would be MORE than greatly appreciated. I have this strange feeling that I am not getting the most out of my home theatre.