1. The ship is used as a literary device to forward the plot of the story such as the witches in Macbeth were used. It sinks and causes Marlow to have to survive a 200-mile trek and be stranded for three-six months. This is why he meets these people.
2. Marlow will survive his journey no matter what happens to others.
3. The doctor measuring Marlow's head, talking about internal changes.
4. Should we believe the narrator or no?