You REALLY need to do this research yourself. It appears to me that sound system hardware from 2016 models will fit into 2013 cars, but you're going to have to double-check, because these things are expensive enough that you don't want to be wrong after having already paid for it.
As for the camera, it may be that the wiring doesn't exist in your car to support it. Again, you'll need to do the research on your end. If it were up to me I'd have a single wiring harness for across the entire model line, but that's me.
Digging a little deeper it looks like the harness that plugs into the back of the radio unit will have the wiring for the camera, but you'll need to source the trunk lid harness for the camera - get it from the organ donor when you harvest the camera.
It looks like you'll need to do some programming work too, so be ready for that.