亚当、夏娃堕落前：

(1)。蛇是罪的化身，是否可以说亚当、夏娃堕落前罪已在世界上存在了？

Satan fell before man. See Isaiah 14:12-15; Ezekiel 28:12-19; Luke 10:18.

(2) 亚当、夏娃吃园中的果子，是否说死亡已在世界上存在了(果子被吃了，死了)？

Death is a part of our cosmic economy. Death is predestined and designed into our cosmos according to the Creator's foreknowledge and foresight.

(3)。如果亚当、夏娃不堕落，人类不断繁衍，是否会把世界挤满了？

See answer above. No such if, given God's transcendence and foreknowledge-based creation.