Re: THE WIZ film--
Diana Ross always considered herself to be in the same category as THE Classic Singers (like Judy Garland!) so she thought she'd be the PERFECT entertainer to play the part of Dorothy in THE WIZ. (She had said that playing Dorothy was always one of her dreams.)
When she heard that Motown was going to film THE WIZ with orginal star Stephanie Mills, she went to long-time mentor Berry Gordon (President of Motown, he helped the Supremes get started) and got down on her HANDS AND KNEES and begged him to be cast as Dorothy.
Gordon was initially aghast ("You're too old to be any damn Dorothy!") but Ross persisted, pointing out that Garland wasn't a teenager when she played role and gave a few suggestions as to how film could work if she was in it.
Finally, against his better judgment, Gordy gave up because Ross owed Motown one more picture and realized that with Ross in movie, film would have a "pre-sold" audience, no matter how BAD it was.
So, he told Motown Ross would be cast as Dorothy and ordered screenwriter Rob Cohen to write a script that would make sense with her in the role.
The rest is ... a VERY EMBARRASING moment in Hollywood History!
P.S. Ross has not made another movie since THE WIZ.
"I say YOU'RE the CUTEST one. No, I say YOU'RE the CUTEST One. And we go on like that from dawn to three."