I am going to be running a 4 channel amp to my inside speakers and a mono amp for my subs. Should I get a crossover or an EQ to keep the right signals going where they should?
that'd be a crossover. some head units have both an EQ and an XO built into them, like eclipse and alpine at the higher end. some EQs also function as a crossover, too. These usually have one or two sets of inputs, and F/R/S outputs, offering both equalization, and fader/balace/sub control
"..the preamp outputs have a selectable low-pass crossover that can be set to 50Hz, 80Hz, or 120Hz. You can adjust the subwoofer volume from -6 to +6 using the front panel subwoofer volume control."
SO I just run that to the sub amp and the normal connections to the other amp and I should be fine correct?