Well I was hoping to avoid that option but it seems I may have too. I mean from the looks of the pics it looks like #1 is part of "Head of Family"; #2 unless it is part of a different route, should have been unlocked with "Schoolmate"; #3 looks like it is part of "Control"; #4 I have no clue which route that would be but looks like Max and Alice are shopping; #5 looks like it would also be part of "Head of Family", and last #6 looks like it is part of either the "Arachnophobia" or No Candy nighttime foot massage and choosing morning shower (which I have done more than a dozen times).
All your assumptions sound right to me and you do good to play the storyline.
The chosen path basically only effects Ann's storyline, so you can unlock most pics in one playthrough. Follow the walkthrough and you're good.
The shopping will happen once a certain point in Alice's storyline is reached. As usual don't focus on one opportunity, especially in Alice's case it's needed to play all of them, since they depend on each other. The end of her content will be, when you get to punishe her in the garden again going a bit further than usual after getting punished by her again. Once you did that, you get extra scenes as reward.
After helping her on the couch you can choose either to visit her in the bathroom later or to get a reward the next morning in the shower (which can only happen if she showers alone). The (so far) final night spider prank is also repeatable, having at least one additional variation.
You can keep the current game version, so you can unlock everything even after the next version is released (but you shouldn't take that long). However ... while it is possible to use different savegame slots, the persistent files might conflict with each other if Alexey won't use another name for the directory in Appdata.
