What did the winner of the hunt receive in Where the Red Fern Grows?Who went with Billy's father to recover Rubin's body? What was the headline of...

The grand prize which is to be given to the winner of the championship coon hunt is a gold cup.

Billy's dogs are the winners of the championship coon hunt, and they receive two other awards in addition to the promised cup.  Little Ann wins the competition for the "best-looking hound", and receives a small silver cup for her victory.  And when Billy's hounds win the grand prize, they receive an extra award in addition to the championship cup, which will have their names engraved on it.  That extra award, the best of all, is a box of money, over three hundred dollars, collected from the contestants as a jackpot prize.  With that money, Billy's mother and father are able to achieve their dream of moving to town so that the children can go to school (Chapter 18).

Grandpa goes with Billy's father to recover Rubin's body.

Papa says that Grandpa "is the only man in the country that has authority to move the body".  As he sets off to get Grandpa, he tells Billy to fetch Old Man Lowery and the Bufords, and to have them meet at Grandpa's place.  After Papa and Grandpa have retrieved Rubin's body, they are on their way to the Pritchard's house when they run into the Pritchards, who have begun to search for Rubin.  Rubin's brother had been incoherent with terror when he had come home, and had been unable to tell the family exactly what had happened or where Rubin's body was (Chapter 8).

The headline of the newspaper that Grandpa showed Billy read "CHAMPIONSHIP COON HUNT TO BE HELD". 

Grandpa has always wanted to take part in "one of those big coon hunts", and has been keeping records of Billy's hounds' accomplishments.  He believes that Old Dan and Little Ann will be able to hold their own with the best dogs around, and has already paid the entry fee so that they will be able to compete (Chapter 14).