Beautiful new ones!
A good rule is not to post anything from Livadia.org, or Beinecke. However, if you're familiar with Beinecke, you can spot the new ones added and post them. Most of us probably haven't been through them enough to spot the ones just added.
About marking photos, I stopped doing it. What is it to me if someone wants to take it and sell it on ebay? I don't own the picture, I have no right to tell them they can't. Colored photos would be different, though.