Lacho:
From memory it is just one topic but all three of the questions you posed can be summed up quite nicely in one essay. Just remember the good old days of essay writing in High school. Topic, Introduction, 3 good points and a conclusion.
Don't get too worried about the essay. Essentially they are assessing your ability to write down your thoughts in a coherant way using a high standard of english. The standard you should be at after finishing high school that is.