The graphic they added to the Mystery Booster packs had a square background, and the one they used for The List seems to have a rounded background, which creates a telltale difference in the shape of the cards border as you can see on Chatter of the Squirrel and Ancient Den as well as subtle changes in its placement on new border cards, as seen on Boros Challenger
To find him, use Friends on the Other Side or Maleficent, Sorceress to draw more cards from your deck and get through the chaff
Totally Lost depicts a poor little homunculus named Fblthp who is hopelessly lost among a crowd
That said, let's get into those aforementioned characteristics
Okay, but what about the second theme, Elves
Athreos, God of Passage and Athreos, Shroud-Veiled are two different cards for the purposes of deckbuilding