The light: I found the 1% to be a bit too bright as well, but there is a nightmode mod on these forums that fixed it right up. (It allows you to reverse the colors. Much easier on the eyes when it's dark.)
Wifi: I rarely use it. I do sometimes look things up and then I just turn it on, look up what I want, and then turn it off again. But I do that with all my devices-not just ereaders so it's more of a habit than anything else.
Clock: That was the hardest thing to get used to when I switched from a 1st Gen nook to a nook ST. I've been without the permanent clock since May 2012 and have since gotten used to it. I'm guessing the clock takes up more battery usage if it is constantly displayed. No idea if there is a mod for keeping it on or not. Might be worth a look.
I've only had my kobo glo since xmas - so hopefully someone will be able to help you with these better than I can.
