1. As for going to school. I fasted while I was in the university; I never went for more than a week at a time. When I was fasting I found it helped me in school, when I fast my mind becomes more alert, I pick up more information in class. Long reading assignments would leave me tired. I also would take a nap in the middle of the day if I felt like I need it.
3. Peoples opinion on the amount of water to drink vary, but if you are detoxing, more water will help flush your system. As a minimum I try to drink 1/2 my body weight in oz. so for you 125/2 = 62.5 oz of water, or eight glasses, this is a minimum.
As for your other question, me being a guy, I really don't know how your body or any others woman's body will be effected by a fast.