Yes. Seriously, all forms of animation are just ways of achieving different sorts of styles that can't be done in live action. My personal preference usually lies in things that are a combination of CG and traditional (the last few Miyazaki movies with the exception of Ponyo are good examples of these) but all of it has its place depending on what exactly the director is trying to achieve. Howl's Moving Castle is a great example of both... the titular Castle is almost exclusively done in 3D and would have been borederline impossible to animate traditionally (at least on a reasonable budget). On the other hand, there's a bit in the movie where the characters are cooking eggs and bacon and the traditional animation there can only be described as "showing off" as it's utterly outstanding.
Yes, first few seasons all by hand, outsourcing the thousands & thousands of frames (per episode) to not only other animation studios, but studios in other countries. Same thing with cartoons from the '80's. In fact, you can see an increase or drop in quality in art in some shows based on where it was done, like "Batman: The Animated Series", where in one episode the Batmobiles litterally hugs a hills going over it, and the whole batmobiles warps to a curve (there are more examples). You can watch Disney specials where they shows animators drawing each frame. And it should be noted each frame has more than one drawing, with layers. While "The Simpsons" and "Futurama" are likely not using that even in rare instances, instead going the cheaper route, it's a safe bet animated Disney moives are still using traditional drawing (for the most part).