Yes and no to the channels question you could run one sub to each channel but can also put multi subs on one channel if amp s powerful enough and you get the right ohms Which is resistance. oing lower in ohms means more power but if you go lower than the amp is built for good bye warrenty and amp in most cases I suggested the 600 watt becuase the brand is a pretty decent one and you will get the power that is listed and last i looked those subs take like 500 watts rms so if you get that amp you can keep gain set low and what not and still sound good
+1 on custom box makes HUGE difference