The excerpt that tells the White family's uncertainty on the Major's story would be when Mr. White said:
"If the tale about the monkey's paw is not more truthful than those he has been telling us," said Herbert, as the door closed behind their guest, just in time to catch the last train, "we shan't make much out of it." This is because they are not sure what is true about the information that a stranger told them in the train.
Question 4 is true i dont know about the rest
The correct answer is the first one: compensate.
The voice is the narrator who is telling the story you're reading, not necessarily a character from the story. While the point of view is the point of view of one of the characters from the story, telling his own feelings and visions.
Hope this Helps! :)