my cpu/battery

hi fellow droiders
first phone specs:
samsung s4 mini SGH-i257m rooted

now question:
I have no frills CPU app and can anyone explain in non technical terms what the governor settings also i/o settings do like what each one means how it effects CPU and/or battery?
I also use opg pro battery app full superuser lets me access CPU and as I'm writing this but I don't know what setting to use to to get the most out of my battery. I also have powersave on that is stock with s4. does this drain the battery when on? one last question... in the volume you have the setting gear beside volume slider and under notifications volume slider there is a system slider. what does the system do?
thanks for taking the time to read this and thanks ahead of time for those who reply
my email address: sparky_rad@yahoo.ca Facebook sparky B sparky