On top of champi's advice, google it, and choose de image tab. Also try google earth, you should have tousands of image on location.
It is very nice all year round, specialy in summer. The citadell is still active as base of the royal 22nd regiment, but can be toured with guides.
Also quebec portal should have tons of info. And do not worry if you don't speak french, you will always find a way.
Have a nice trip!