Oh, my characters come from all ends of the spectrum, so it's only natural some of them swear quite a bit. Language should be directly tied with the character's persona (defined by all the variables of social layer, education, general attitude, heritage, nationality, etc.)
I personally find the entire clearly set Good vs. Evil dull, but that's probably why I find it difficult to enjoy classic fantasy. Nothing is ever
black & white, unfortunately, and thusly, I don't like it being portrayed as such in most works of fiction. Then again, there are some exceptions to the rule, but it takes quite a bit to make up for such a classic plot motivation. One such exeption would be (all strictly in my opinion, of course
) David Eddings. His series are all clear-cut classic fantasy, but they are still enjoyable to read, nonetheless. (edit: sorry, this came off as a bit snobbish - not my intent. It all boils down to personal likes and dislikes.)
That's usually how I go about writing as well, though I always have a rough plotline in mind to follow, but individual events are usually simply created in the spur of the moment.
As for languages, I'm working on quite a few myself. Got norwegian bokmål, and norwegian nynorsk (two entirely different languages, actually - they're a pain), german, rudimentary french and fluent english down. Next up is latin, soon followed by arabic. Always wanted to do russian, though. Intriguing language.