As long as an opponent controls a creature with flying not named Escaped Shapeshifter, Escaped Shapeshifter has flying. The same is true for first strike, trample, and protection from any color.
Enchant creatureEnchanted creature gets -X/-Y. If that creature is attacking, X is the number of snow lands defending player controls. Otherwise, X is the number of snow lands its controller controls. Y is equal to X or to enchanted creature's toughness minus 1, whichever is smaller.