1/1.1: I don't want to spoil anything yet, let's just say this storyline will be the main focus of chapter 2 ;) And the mansion will get more rooms as well.
2: It's planned, but more towards the end of the games' development.
3: Actually, this was a good time to bring it up, since we're currently upgrading the game code for the next update anyway, we'll take a look at this.
3.1 and 4: We plan to add locations outside of the mansion soon, yes, and of course some of them will be used for naughty events :)