Hey Kristan,
Congratulations!!
Montreal's awesome for students and youngsters! If you like to eat, party and have tons activities, this is the place.
I like to refer people to :
Traveller | Tourism Montreal
During the week, we go lounging after work, anywhere on Crescent, St-Laurent (quite posh) or Outremont and Mile-End for coffee.
During summer, there are plenty of festivals and sidewalk sales.
On Sundays, whenever sunny, I like to go hang out with my friends at Mt-Royal Park. But we really take our sweet time and just stop at any store we see along the Mt-Royal Avenue leading there. If cupcakes are your thing, you must go to Les petits Gateaux.... best cupcakes EVER. They usually run out of the coconut ones too T_T
Saturdays? Party. Of course. Places: Downtown, St-Laurent, Crescent.
Hope this helps you a bit.
Bienvenue à Montréal.