There is not too much information out there on this. I am using the Metra Harness with the RCA out's. Im not a audio installer by any means. But I want apple carplay and a back up camera.

The halo 9 has subwoofer pre outs but the metra harness doesnt. Is that okay? Does the amp send the signal to the subs on its own processing?

The ground wire is a bolt loop, is it okay to connect that to the metra harness ground? Will that be sufficient or do I need to ground it to something different?