I don't quite understand what you mean in Situation 1.If your card is stolen, that's very different than having a hold on it.Are you trying to ask what you say to the company when you call, or what the result will be?
In Situation 2, I believe I've heard it said that "a hold" has been placed on your card. If you have a low credit limit, by "holding" that much for themselves, the hotel ensures that amount is available to them so other vendors can't use that money. Otherwise, it could be possible that when you go to check out and they want to charge your card for the amont of you stay, you could have reached your limit and they would not have any funds available to pay for your stay.