Misc: In 1917 British Royal family changes its name from ---------- to Windsor. ?

Questions

Which jazz trumpet virtuoso is credited as having invented scat' singing?

Which 9-fingered pop pianist starred in the film Its all Happening?

Who, according to a song, damaged her foot on a piece of wood and fell into a raging torrent?

Which musical includes the Barbara Dickson/Elaine Page song I Know Him So Well?

Which musical was based on the play The Matchmaker?