A: Unless it is specified that an appropriated card goes into your hand, you should assume it goes in front of you, just as you should assume the only valid targets of theft are cards in play unless otherwise stated. In general, a card will maintain its in- or out-of-play status even if it changes ownership: if it starts in play in front of someone else, it it stays in play in front of you. Exceptions (like Zap a Card, or Use What You Take) state the origin and destination of the card.

Thus all stealing of Keepers, whether via an Action (like Steal a Keeper) or Free Action Rule (like Plunder), or Keeper Power (like Captain Kirk) involves taking a Keeper from in front of someone else and putting it in front of you.