Well the only thing I remember from BO2 concerning fire rate was if you had the select fire attachment equipped in core. That's the only time I remember fire rate being displayed. As for Ghosts I'm not sure. As for heavy duty mode I think you mean hardcore. This is all I play and yes there is a difference in how much damage you take from enemy fire. Also no HUD. No your DS4 controller will not charge unless the system is on or in standby mode. I've never had my volume stop working after taking mine out of standby so I think in your case it was a fluke. I always keep mine on standby when I'm done playing because if any updates for the system or one of my games gets released the PS4 will automatically download and apply the update while the system is asleep. If it is off you will have to apply the updates before you can play and takes several min. depending on the update file size. And I assume when you say blue lights you mean the light bar on the front of the controller? It's main function is to be visible by the playstation camera. Also depending on the game different DS4 controllers will have different colors to indicate controller 1, controller 2, and so on.
Your reply helped with several questions/concerns, however regarding heavy duty I do not mean Hardcore. If you go to "standard" then "heavy duty", that is what I mean. I understand your answer regarding the controller lights with the camera. I understand what you said, but do not understand how that has to do with making the controller more accessible in dark environments. I really do a appreciate the time you took to address several questions. Attitudes like that are what breed growth.
1. Fire Mode - I always assume someone has jacked up the weapon so I usually test fire it or expect the absolute worst. There is no display to show you - sadly.
2. Heavy Duty mode basically adds 1-2 bullets more of health on some guns. Some guns do not change at all at close to medium and only change at distance. Snipers are 2 shot kills outside of headshots.
3. Blue light is for the playstation eye/move/etc stuff. Other minor things, basically worthless and battery draining.
4. I've had sound being gone issues as well. I just power cycle to fix. I turn my ps4 off when done and don't leave it in standby.
5. Power on the ps4. Treat it like it is a computer because that is what it is. Powering it down normally should be fine. Don't just pull power or force it to power down too often.
6. Framerate - There is currently a bug in the ps4 version of ghosts resulting in framerate issues. They are supposed to be working on a patch.
Hope this helps.