Sorry for the delay on questions.

Yes, a backup camera can be installed.

No, I did not swap out the amp. I'm using the factory amp for everything. I also kept the factory wiring harness to the amp in place and did not convert to use all 4 amps. All is being driven just as the factory setup. By doing this I can reinstall the factory radio anytime; but I don't see me doing that.

The sound on this does not have me wanting to do anything else. It's loud and clear and punchy.

FYI: I've still not had to replace the stock woofers. They are still kicking and working fine.