Commute with bicycle on Yonge St., is it a wise choice?

A dumb question here: Due to job duty change, I need to be back to office a few months later. My office is not close to subway station, so I'm thinking of riding a bicycle. I have never done that before in Toronto, and I have several doubts

1. Is riding the bicycle along Yonge St. (Davisville Ave to Dundas) safe? Is there a separated bike lane?
2. Can I still ride in winter? How uncomfortable it would be for riding 5 km?
3. Furthermore, in winter, will the bike lane be used for dumping snow? (it happens in some cities)
4. Is there an online guide or book for newbies like me?

Thank you for your tolerance to my questions