Read back and see you installed two amps. Thanks for that.
Re: HVAC - did you change the 'Car Type' in the advanced settings?
To access: Settings > Advanced > enter password [mine was 8861]
From there, you can affect different things. If it was working and stopped and you didn't change anything, you may re-check the connections to the black box on the back. Mine worked fine out of the box on a 2004 LC.
The no sound issue remains the problem [and the camera, but that's an aftermarket install fix]. Will purchase the Metra harness and see what's up.