to answer your previous question, no GPS is not always on even when its ON. Unless you have the weather channel app set to locate your location for weather updates or if you have google latitude on. Other 3rd party apps may use the gps also but i dont know what apps you have installed so im not gonna bother listing them.
So i wouldn't worry about turning off GPS, the only thing i would turn off would be wifi if im not at home or school. The only time ive turned off GPS is when the google home page on the browser kept trying to find my location and the GPS icon wouldent go away even if i exited the browser, but i turned that setting off in google settings and now its not a problem.