That would have to be Watchmen. Yeah, they didn't follow everything from the comics, but it was good enough and I enjoyed it. I also like other things like Batman, Superman, Spiderman, V for Vendetta (that was from a comic, right? Or a book, not sure), etc.
None. Sad to say but I don't spend my time reading much comics now. I used to read some comics when I was younger (Doraemon), but I don't think that has been made into a full fledged movie.
I would have to say Batman. The spiderman movies were good but they made too many and the third wasn't as good as the first two. Watchman was very nice as well, but batman will always rule all.
They've been developed into movies? I doubt so....
The first one I have never heard of and I don't think that has a movie. Fairy Tail doesn't have a movie yet. And Full Metal Alchemist definately has two movies.