I'm not sure what bus number it is but the hotel staff will know.
There is a frequent, every 15 min or so, TTC bus from all three airport terminals to downtown. Lots of our F/A's use it.
Downtown there are lots of great bars, restaurants and things to see. the harbourfront should be a grat place to sit outside with a beer and relax. If you want to excercise head on down there for a run, you can also rent rollerbaldes.
You should have fun.