2. To have the bass "corrected" by using the built in room optimization program.
3. Placement of HT3's vs. subs
I agree with George on these, especially if you can place the subs into the room somewhat. Ideal placement is basically in the "nulls" for room modes, which minimizes the interaction with room modes. The correction will also help and will smooth the modal response. The combination of the two would be killer. Having said that, I only use my (three) subs for movies. But that's party due to time considerations (recently, I basically have had very little time to fiddle with my system), monetary considerations (room correction entails getting another piece of electronics, yet more interconnects, etc.), and placement considerations (I cannot really move my subs into the room, but can keep them away from the corners). If you have time, money, and room, then I'd recommend trying this.
