1) Who were Buster Keaton, Charlie Chaplin and Harold Lloyd, and why were they so important to the success of the Hollywood silent era?
They were comedic actors who rose to fame during the silent era of Hollywood. They became global stars, as the silent films were accessible by any culture.

2) Name a film starring each of the above.
Sherlock Jr (dir. Buster Keaton, 1924)
The Kid (dir. Charlie Chaplin, 1921)
Safety Last! (dir. Fred  C Newmeyer, 1923) – starring Harold Lloyd

3) Who were the Italian and French equivalents of Charlie Chaplin?
Toto was the Italian equivalent, and Jacques Tati was French.