In 'Thelma & Louise', which actresses play the title characters?

In 'Titanic', what is the name of the necklace's giant blue diamond? In 'Jaws', what is the name of the police chief? In 'Jaws', who plays shark hunter Quint? In 'Close Encounters of the Third Kind', at which landmark do the aliens land? In 'The Sound of Music', what is the family's surname? In 'The Sound of Music', which actor plays Captain von Trapp? In 'My Fair Lady' (1964), who plays Eliza Doolittle? In 'Singin' in the Rain', who performs the title song dance in the rain?