Why was Ebony such a miser to the point of putting her large crew in fleabag motels while keeping the money she could have used to give them better accommodations? Because it's heavily implied she lived hand-to-mouth in her early life (to the point where she had to create a Christmas tree out of construction paper at school to use as an actual tree).
Marli's death, via a car crash. As bad as it was (and even worse, according to her, she killed two other people in the process as well), note even though it's not specified if they were in the car with her, in another car or were just two pedestrians she hit she takes off her head to show to Ebony that she is dead. She could have just let her put her hand through her spirit, but her doing that more than implies how she died. Plus, the way her neck looks shows how savage it was. And it gives credence on why upon seeing her crew badmouth her in the present day and hearing back-up singer Tina quips "Off with Her Head!", she gets so angry that she fires her on the spot, not just because she wished death on her, but she made light of her best friend's gruesome demise.
The condition of Ebony's body, as seen while she was viewing her Bad Future -laden episode of Behind the Music. She was apparently so hated, that she was left to rot in her bed. Plus, like with Marli, we're given a glimpse into how she died: she tends to mix alcohol with pain medication, which can be deadly.
