for the RCA's it depends... is it a 4 channel amp? if so then YES if your going to be running all 4 channels, for the second question, the HPF is a high pass filter, it "passes" out the lower frequinces, the LPF is the oppisite, for the 3rd one, + or power wire, would be the power wire that goes from the amp to the battery, the GRD or - is the ground which goes to a bare metal spot on the car, the system control is the remote wire which runs to the headunit or stereo to turn the amp on or off