Mostly answered multiple times above...
1. No, it would require too much effort as all the in game CGs are static. This was kinda worked around by Anna's costume returns and pills, so hopefully we will get some additional ones soon. Though any costume/appearance changes will be limited to events and the studio.
2. More than likely, guess we will need to see what the additional love/slut route events bring.
3. Doubtful, this would bring even more complexity to a game system that already requires quests to be completed on a set day.. Adding a day/night cycle would just add frustration...