1. For Nina, I think you just have to complete contracts and keep on checking on her in between contracts.
2. The duo at the asylum won't stop until you catch the ghost. After that, you have to look for them (there are several locations they'll go to, sofas I think).
3. What do you mean by the ticket in the sofa?
4.
You must be registered to see the links
which lists all animations so far, and says how to unlock most of them.
Edit: I don't think you can fuck the girl watching the porn movie or the other girls getting fucked at the Sunflower Streets level. At least not yet.