Yes, KaDee's part was definitely THE scariest part in the film. She's in bed and something grabs her inside the bed and YANKS her under the covers (and she's gone/dead).
I think Clea Duvall was married to Tom Cruise's cousin Mopather - maybe they were the people Sarah Michelle Gellar rent the (haunted) place from? Not a big part And Bill Pullman was in it too.. it is rather vague, now. I know he gets thrown off a roof, because there was a photo of him posing with the dummy of him (that got thrown off the roof).
Shimizu was such a great director, and Jason had such a good time working with him, and in Japan. I think he expected Dragon Wars with the Korean director would be a similar experience, but they were totally two different type guys and I don't think he enjoyed making Dwars or working with that other director (who seemed like a crazy egomaniac) nearly so much.
Thanks, I've never seen that behind the scenes Grudge picture before!