Phone dying before 0%?
This is an issue that frustrates everyone, and me included. I would be using my phone, and all of a sudden when the battery was 40%, the phone would suddenly turn off and start the restart cycle over and over. There is a solution that does not require you to reset your phone completely. Generally, we like to use our phone while its plugged in because we think that it is efficient, but actually doing so is not healthy for the phone. Just like you, the phone needs to be left alone while it is recharging. If you were sleeping, would you like someone to be poking and prodding you? No! You would get a horrible nights sleep the next morning. The same thing applies to your Note 4 or any device. You can prevent this issue by powering your phone off before plugging it in to charge. Keep it off until it reaches 100%, and do not overcharge your phone. If you use it while charging, you're actually overworking your phone and it can cause the problem to become worse. Also make sure you're using the official charger that came with your device, or an official samsung charger. Many 3rd party chargers will not properly charge your Note 4. A happy battery equals a full and healthy battery cycle.
Not all phone manufacturers would agree with you since some phones turn on when plugged in to a charger. They will not remain turned off while charging.
Yes, that is what Samsung devices do. Some phones will turn completely on when charging even if you plug them into a charger when they are turned off.