UnScramble this Word: h p l d a o s i?

Questions

"keep that schoolgirl complexion"?

Which queen had menstrual cramps eased with marijuana?

Which river is dammed by the hoover dam?

Which river passes through germany, austria, slovakia, hungary, croatia, yugoslavia, romania, blugaria and ukraine before arriving at the black sea?

Which shakespearean character provided the plot for verdi's only comedy?