Answer:
In my opinion:
1) information, promotion, edvertising
2) Propaganda is used to try to make people think a certain way.
3) In August 1916, a famous British film was shown in cinemas about the Battle of the Somme. It was the first time people at home could see soldiers in the trenches, guns firing and wounded men. Filming and reporting from the Front let people find out what was really happening in the war. Although it was upsetting, people were glad that they could finally see it.
That's why might propaganda have been used during WW1