Reaction: After you win a challenge in which Ser Mark Mullendore is participating, reveal the top card of your deck. You may put that card into play. If you do, place Ser Mark Mullendore on top of your deck (cannot be saved).
There is no "Then" in this wording, so I assume technically the new card entering play and Mark leaving play are simultaneous game events, correct? i.e. technically there is no moment in time at which Mark and the new card are both in play?
2) Bonds of Chivalry
Action: Choose a participating Knight character you control. Stand it and remove it from the challenge. Then, you may kneel another Knight character you control to have it participate in the challenge on your side.
There is "Then" in this wording, so I assume the chosen Knight character must both stand and be removed from the challenge, in order for another Knight to be able to participate, correct? e.g. if i attack with a Green-Apple Knight (who does not kneel to attack), then play Bonds of Chivalry and remove it from the challenge (without standing it, because it is already standing), then I will be unable to kneel another Knight character and have it participate, correct?