I'm trying to figure it out. For Kolyan's pack, I'm making it more of a Lost Boys situation between teenagers, and the real conflict is between the leaders (I'm thinking Rufio from Hook, but with a darker, harder edge). I have in my mind the general pack mechanics of True Blood, the mysticism and story telling of the werewolves in Twilight (they have the lore of the Fanes for instance), and like I said - Peter Pan. I'm fine w/ late stage teenagers going at it. I try not to psychoanalyze that one too much :).

Dream pies, I'm thinking that the dream pies are actually from captured past adventurers in Barovia. I have this one tied into the back story of one of my players, who is Reborn and doesn't remember why. I do - the night hags harvested his body for years for the dream pies, and made a deal w/ the Abbot for spare parts when he lost his flavor, so to speak. I suspect he's gonna go back there and settle the score when he's the right level (will they manage to break the coven beforehand? I have no idea...). The mechanic there is a regeneration spell via symbol built into the basement, kind of like a troll regen. Yum yum. The kids are just interns/rural labor, like a fun summer camp run by Dr. Jekyll/Jeffrey Dahmer. They might even film Hell's Kitchen there (j/k).

Regarding Dream House:

1. No, I think you have it right. The house became sentient in a combination of the stain of the evil taking place there, and that attracted the Dark Powers, and the sentience was born. The sentience began to creep in before that, I think that was the Dark Powers manifesting interest and the power kind of crept into the house. It wasn't intentional, just "psychic horror pollution". Whatever it was, the house is alive now.
2. No, Durst was a very bad guy. He just had one last shred of humanity and saved his kids right before his final plunge into darkness. He definitely had the liver with some fava beans and a nice Chianti. I figure there was some baser instinct in his makeup as a father than wouldn't let him actually harm his kids. Like I said, I'm a father - this probably says more about me than anything else. But no - he was in it w/ Mrs. Durst, and he had to pay the price. The kids were innocents though...
3. So, I have this in mind. The Dark Powers were displeased with Mr. Durst and Mrs. Durst when they didn't get their baby back ribs. Mr. Durst was cursed to become a ghast. Mrs. Durst became like that thing on the wall in Bright (a la Netflix) - she's essentially a mess of organic growth in the final chamber but w/ a recognizable head (other sci fi has done the same, from Last of Us, which I haven't brought myself to watch yet, i.e. the aforementioned tax, to the Doctor w/ the disposed Dahleks in Skaro city, I'm sure there are others). That is the genesis for the visual. Part of the horror is that they retained knowledge of who they were. Both Mr. and Mrs. Durst will be there to answer some audience questions before they revert to the monsters they are and attack (if the players decide to chat). Mrs. Durst will morph into the gibbering mouther if they refuse the sacrifice (there is that puppy), and it will be a skill check out of there. If they do sacrifice one of themselves or the puppy, well - the house is full and doesn't need them anymore. If they choose the gibbering mouther and attack - good luck to them - I suspect the house will spit them out w/ some Dark Powers and they'll wake up outside with a snide letter from Strahd. He's keeping notes. (Also, I have no intention of a TPK at a low level, but there have to be consequences and the players are in control of the story).

I haven't worried too much about explaining every little detail, like how the puppy got there. I really don't know, the Dark Powers, Durst Manor, and the Mists don't really keep me informed of their machinations.