The writer's world is another way of saying; "The scene that is being set for the story to be told. Time, Location, Characters, Mood, Situation, etc.
For example, If you were telling a story about Dungeons and Dragons, perhaps you would mention that the main characters, Corlon, a Fighter and Esmerelda, a Sorceress are Trapped in a Dragon's Cave guarded by a Large one-eyed Cyclops and a Very Large Hungry Green Dragon. And so on.
A prepositional phrase starts with a preposition. Given that the preposition in this sentence is the word <em>in, </em>the prepositional phrase is in the contest. The word it modifies is paint.
Where does Devon want to paint pumpkins? In the contest.
Approx. 550 miles in area
If there are is no specific painting or poem, I believe the answer is beauty.
