(image borrowed from Disney Wikia)
The chief creative officer of Pixar Animation Studios, John Lasseter, is also the chief creative officer of Walt Disney Animation Studios. The president of Pixar Animation Studios, Ed Catmull is also the president of Walt Disney Animation Studios. So basically the head guys at Pixar also help out with the other Disney animated movies!
(image borrowed from Wikipedia)
When Ilene Woods died in 2010 it was from causes related to Alzheimer's disease. Based on comments she made regarding watching the movie one last time, it seems likely that she forgot she was the voice of Cinderella.
This was just sooo sad to hear! Alzheimer's is something that saddens me. Though my grandparents never had it, my grandpa did start forgetting things when he was dying from liver cancer.