1. In your opinion, are the ghosts real, or are they manifestations of the Governess's imagination?
Yes, in my opinion the ghosts are real. The Governess knew exactly what the ghosts looked like and she never knew them.
2. What exactly is so scary about Peter Quint (well, aside from the fact that he's dead)?
Peter Quint is trying to possess Miles. He also tried to seduce Miss Jessel. If that isn’t already enough, he tried to take over the house when his uncle left and control everything in it. But, he did terrible things to the people in it with the power that he had. He also stands for the idea of sex. Peter Quint is very controlling and manipulating.
3. Why are the Governess and Mrs. Grose so disturbed by the idea