Clark, Lakeville, Minnesota
A: The days-of-the-week intros were filmed in color; you can see the color versions on the Walt Disney Treasures DVD Mickey Mouse in Living Color, Volume 2.  Walt Disney often filmed his early television shows, especially animation segments, in color, believing that they might have some future use.
Jay, Los Angeles, California
A: The writers would have to do research for the stories, but the characters and their personalities are already established in the animated features. For television series, the aim is always to have the characters look like and act like the ones in the original features, but sometimes a few revisions have to be made.