If I wanted to disable the nvidia GPU to increase battery life, what's the best way to do that? Would it be disabling it in the device manager or should I set it in the nvidia control panel?
Either in the nVidia control panel, or if your system has the option, in Setup check for a setting there -- if you disable the nVidia GPU at the firmware level, it will accomplish the same thing.
Is there a way to have the preferred graphics processor set to auto in the nvidia only when the laptop is plugged in? That would be ideal.