what military decorations were created? who received them?

From the text:

"The animals decided unanimously to create a military decoration, "Animal Hero, First Class," which was conferred there and then on Snowball and Boxer. It consisted of a brass medal (they were really some old horse-brasses which had been found in the harness-room), to be worn on Sundays and holidays. There was also "Animal Hero, Second Class," which was conferred posthumously on the dead sheep."