Last I heard, Kidman was inking a deal but it wasn't a lock.
This site is ahead of IMDB and says Kidman and Ferrell are a lock; no other cast set. Ferrell's been a known deal for about a month, I'd guess.
I invented saying Kidman and Carrey were the perfect Sam and Darren.
As for nuns, they cropped or hacked or shaved their heads, but didn't shave anywhere else. (No doy.) Modern nuns who still wear the habit are few and far between. I know one nun who definitely shaves her legs, but she's the California hot-tubbing variety of nun. YMMV.
