Hi,
re: hydro -- it's your electrical bill.
Toronto can be really expensive, but there are relatively cheap apartments around if you do a little hunting. Check out viewit.ca and the Toronto Star online classifieds to get an idea of what's around.
If you're going to York U and don't have a car, but still want to be somewhat "downtown" -- I would suggest sticking near the NW end of the University subway line (e.g., Dupont, St Clair W. stns) to keep your commute bearable.
Someone mentioned that they want to be close to U of T as well -- living close to Dupont stn might be a good compromise. The neighbourhood is quite nice (north Annex) and Dupont & Bathurst/Spadina/St George is about 10min bike ride/20min walk to Robarts (big U of T library).
York U may have a off-campus housing office that can help you find a place if you're not having much luck.
I grew up in the area, went to U of T, etc -- give me a shout if you have questions about specific neighbourhoods, transit routes, etc.
Good luck! I'm sure you'll love it here