The funicular in the city has the top next to the Chateau Frontenac and the bottom at the Petit Champlain. There are stunning views for sure.
The whole upper and lower city and citadele area is very walkable, although the climb up the hill can be tough.
You can possibly park at the Université Laval and either take a bus or walk (though it’s a bit of a long walk; I did it after a day of wandering and a concert on the Plaines, so it’s doable) towards the Citadele, the Plaines and Parliament, then wander down St-Louis (look for the cannonball in the tree!) and explore the upper city (around Carré Place d’Armes IIRC?).
Walk down Côte de la Montagne and enjoy the fun views and zig zag there (then imagine going down it on ice skates, à la Red Bull Crashed Ice, as that’s where it’s run!) and either go towards the port or take the steps into the Petit Champlain. Wander around in the lower city and visit the shops and museums and then take the funicular back up to the Chateau.
In the evening, go see the Moulin à Images. I saw it for the 400th anniversary of the city, and it’s spectacular. I have a feeling an urban photographer like you will appreciate it!
There’s usually interesting stuff happening at the Market or along the Old Port…there are all kinds of facilities that opened for the 400th and are still used.
Enjoy the city!