useless trivia: What Word Means: A First Name - A Greek Letter - A River Mouth?

Questions

Pop Star Deaths: "Time In A Bottle" hit #1 just three months after his death?

Pop Star Deaths: Freddie Mercury died due to illnesses related to this disease?

Pop Star Deaths: Infamous "Hustle" composer who died at the age of 35?

Pop Star Deaths: Lead singer of the teenagers, who died of a drug overdose?

Pop Star Deaths: Roy Orbison had a posthumous top ten hit with this song?