I would take it to a Honda dealer since it's still under warranty. Also, if you disconnect all four injectors the car won't run. and disabling them one at a time is not recommended.
Car is under warranty so I would just take it in and let them diagnose it.
Yes, but they would have a quiet engine and would be saving a lot of fuel.
Seriously though, your suggestion about taking it to the dealer is spot-on. Comparing it to like models to know whether the noise is characteristic is an extension of that.
I have no problem with trying to see what the problem is yourself, but when it's under warranty and that new the dealer is the only option. Why take the chance on declined warranty coverage after you try to do something yourself and can't fix it and make it worse to boot.