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2. They all come back at once: http://www.cactusgamedesign.com/message_boards/index.php?topic=22516.0
I would assume that Samson would be protected since it is your opponent's card, but I'm no elder. I suppose it would depend on the definition of "opponent's card(s)" in this case.
In order for a card to be an opponent's card, he must own and control it. He would still be the owner of the card he gave you, but you control the cards in your hand, so Samson would not be protected from it. Not that your opponent would ever give you a Samson's Sacrifice anyway...
...what exactly happens when you're protected from an enhancement played on yourself?