food: anything that you think looks amazing, especially downtown. there are a lot of famous montreal delis and restaurants there, the food is pretty much good anywhere! dont go on google to find food suggestions, actually go and ask someone, people in montreal are really nice!

sights: uhhh too bad its not the summer, theres more to see. the best sight however would just be walking around downtown and the old port, you see so many beautiful buildings, just take adventures downtown. Go on the subway/metro! i personally love it. you can go to the olympic stadium aswell, its pretty cool, you can also go to the bell center (hockey arena/concert hall). 

For night life, just have fun, the places are cheap-nothing to get into and the nightlife is great, just explore the near streets for different clubs/bars/cafes

i hope that helped!