Hello there,
1. This is a maybe, but for now it will continue to only be the "go to your room" button.
2. They will have more scenes but do remember Josef and Adrian are still at the house, Adrian will never leave until the end as he is part of many side characters scenes. Some of these places already have events, while not full sex scenes, there are still events.
3. Toni does have a scene that starts at the garage, she could get more content in the future. As for part B, this won't be done, as we have explained before the characters do have a life outside of being available for the MC. This does not remove the possibility (POSSIBILITY, NOT THAT IT WILL BE DONE), that there could be events like when taking Anna to the mall.
4. This is unlikely to happen; at most it would be with the "girlfriend" characters but is very unlikely to happen. One of the options for the endings is buying a new place and inviting characters to live with you. No, it won't be an option for every character, nor you will be able to invite a "harem", the characters in the selection will light up if they have a link the the character selected depending on the story.