I've been playing a bit more, only one or two nights per house though, so I did only scratch the surface but found certain things that made me happy.
Sims actually learn the Medium skill quite easily even in a non-haunted house. The séance table works in nearly the same way. I guess the outcome might be limited, but light is flickering and there are spooky sounds when communicating with the dead. So, maxing the skill should be done within reasonable time, sim won't get that certificate from the Guido(?) guy, but can get it from the aspiration reward store, and with Medium level 5 I don't see why there should be any difference when having paranormal gigs in that career.
Also found that if I enter a haunted house after 9 PM, and miss the "are you ready for some haunting" popup, the night seems to be quite calm even in a haunted house. So if this makes a difference, it's possible to avoid chaos to get a good night's sleep. None in my household woke up even once - but I guess this might be harder later on in the development.
