I think that six and swearing worked in Fall Out because it took place in an empty, hopeless land. I think that the prostitution and swearing helped display that and made it more immersive. I don't think that it will work out as well in Skyrim.
Being able to chop people into little pieces, I think, also helped there, but I say no for the same reasons. Imagine shooting somebody with a fire spell then seeing the target react like the do in Gears of War. I think that wouldn't fit in.
Slavery should be like Morrowind. I just don't want to be the only Orc in the game because all other NPC Orcs are slaves.
I don't think the sixual references and swearing in Fallout had anything to do with it being a hopeless land - both are natural parts of human nature, really. As I've said, I want realism, and I would realistically expect such things in a bawdy Nord tavern at night. Where Fallout was unrealistic, though, was in its violence. TES doesn't need to go nearly that far, Fallout was cartoonish, but it certainly needs to go a bit further than what Oblivion showed.
Somebody pointed out the Dark Brotherhood quests in Oblivion - while they're certainly different to Oblivion's usual tone, I found them to be a bit cartoonish. Lucien was cool, but most of the other people wandering around in there just made me laugh. Too often the quests were played with a comic undertone (murderous dinner parties, mother issues, etc) - usually to great effect, I admit, but let's also have something a bit grittier than the caricatures we had there.