Re: Battery Life
I don't think it matters that much in this case what the screen brightness is set at. Your screen was on for only 15 minutes, was responsible for almost half of the 35% battery drain, which means it used up 17% of battery. Even if the screen was at 100%, it shouldn't use up more than a percent per minute. I wonder if your battery is starting to have problems--how old is the tablet? Did you get it new or used?
The other thing is that you keep your wifi on all the time. This could lead to various apps accessing the web and refreshing data frequently, depending on their settings--and if those apps are malfunctioning, they could be accessing the web too often, which can lead to battery drain. Have you considered keeping wifi off until you need it?