I wouldn't say it was all about a sequel - it was more about keeping with how all the residents of Collinwood were supposed to have secrets. Unfortunately the whole secrets bit was downplayed in the final edit of the film (it's really a shame that in particular the whole exchange between Vicki and Julia dealing with secrets was cut), so the payoff to Carolyn's secret may seem to come out of left field - though there is at least one hint: the remark David makes in the first dining room scene about Carolyn making sounds in her room (and there would have been more if the scene between Carolyn and Vicki in Carolyn's room hadn't been cut). Though it's also true that David's remark is only significant in retrospect once Carolyn's secret comes out - it not like anyone would jump to the conclusion that she's a werewolf simply because of it. Though, because we'd been told prior to release that everyone at Collinwood would have secrets, it really didn't surprise me or seem out of place when it turned out that Carolyn was a werewolf because I'd been waiting to see just what her secret was.
As for werewolf attacks, I got the impression that Carolyn stayed in her room whenever she was a werewolf. And she's a werewolf unlike any other werewolf we've ever come across in the DS universe in that she retains the ability to speak and to grasp what's happening around her. That may be because she's only 14 in the film and thus her werewolf self may not be fully realized yet. Most werewolf stories don't have the cursed person making the complete change until reaching adulthood. But who knows?
But to get to what I really wanted to post about today, I really like how Carolyn throws in the "Woof" at the end of today's quote in the slideshow:
1972 - Carolyn: 'I'm a werewolf, okay? Let's not make a big deal out of it. Woof.'
Particularly how she tilts her head when she says it:
It's perfectly in keeping with the sarcastic nature of Carolyn's personality.
Also, and something that may only interest someone like me who's really into the sets and the production design, but it wasn't until I was taking captures from this scene that I noticed that there's a second fireplace in the foyer on the wall opposite the fireplace where Barnabas' portrait hangs:
But then, we see that wall so infrequently in the film.