1 Aug 2008
The card returns to the battlefield without any -1/-1 counters on it (unless some other effect causes it to enter with some).
1 Aug 2008
It doesn't matter whose graveyard the creature is put into. It matters only that an opponent controlled it when it left the battlefield.
1 Aug 2008
It doesn't matter how many -1/-1 counters were on the creature when it was put into a graveyard from the battlefield, as long as it had at least one.