I can heartily recommend http://www.ridethecity.com/toronto

You enter your starting and ending addresses, and select whether you want a Direct, Safe or Safer route, and it plots it accordingly. If you pick Safer, you may end up biking a little farther, but it takes you down as many available bike paths and calm residential areas as possible. And then less so with Safe, and Direct is what it sounds like.

Another good resource is the aforementioned Toronto Cycling map:

http://www.toronto.ca/cycling/map/index.htm

That site has the PDF maps, but if you hit up any public library (and most bike shops) you can pick up a large paper version for free. If you do take the bus to Yonge/Finch, it may be worth biking down to Yonge/Park Home as there's a library branch right there, as well as a subway station. It's only about a 1K ride from Yonge/Finch.

That ride would also take you past the Cyclepath at Yonge/Churchill. Pretty sure they too have the cycling map.