zobothehobo
Scooby
Maybe not to that extent, but he still probably had some idea of what he could be asked to do. I'm not sure it's legal to force anyone, even an actor, to do that without their initial consent.
I'm going to paraphrase James here... he has said several times that when you sign a contract for a show, they don't tell you really anything about what you'll have to do in the future. But most shows are pretty safe... you see what happens in the episodes and the same thing or pretty much the same thing will happen episode after episode. But Buffy was not like that. The Buffy writers would take it this way and that way and make you do this and that and this and that... and if you weren't comfortable... tough cookies. You signed a contract. So to answer your question, no. they don't have to tell actors what they're going to do in future episodes. But most actors have a general idea... As for legally putting them on camera naked... they can't make you have sex with someone if you don't want to. but they can make your character have sex with another character even if you don't want to. Depending on who you are is how much pull you have. For instance, Sarah also hates nude scenes and she barely has any. James has spoken several times about how sometimes she would jokingly rub that in his face... like show up to set in full winter attire and say "I'm ready for my love scene now!"