She wanted to keep the handmade feel of the show partially to preserve the art of hand made animation, but also to show an homage to the original. The art of handmade animation is rarely seen and trying to keep the handmade feel of the show helps preserve it. Also, she probably wanted to keep the new season similar to the older episodes
MF means mezzo forte in music. It is one of the dynamics to tell you to play loud or soft. So in this situation, mezzo forte or MF is telling you to play moderately loud.
