I'm guessing the Landmarks are the bidding thing. Each Landmark has a unique effect like "At the start of each of your turns, +1 card". At the start of the game, you put out n Landmarks for n players (if you draw a random Empires card from the 10 kingdom cards, like determining whether to play with Shelters or Platinum/Colonies). Then, players bid VP on an available Landmark. You take turns bidding (like in Evo and probably other games that use that mechanic) until one player is stuck with the last Landmark for 0 VP. Everyone else starts the game with negative VP equal to their bid, and whatever Landmark they won.
I don't think the bidding will be for cards in the game. Possibly for events, but I sort of doubt that too. It would slow the game down a lot and might feel unfair if the bidding happens at the wrong time (on a bad hand or whatever). Bidding is a totally new mechanic and Landmarks are a totally new thing, so it would make sense that they go together.