The failure to sense emotion or thought is likely because the shadows are so different they can't read them properly. Lyda (sp) did scan a carb and felt how they killed Kosh from doing so. In the end of the war it was very clear the Shadows had emotion and their tactics showed intelegence.
I didn't think of it back two years ago, when I made my last post, but I don't think Lyta got that image from the Shadow ship. She saw it when Sheridan touched her, after
she already severed the connection to the Shadow ship, thinking she couldn't block it.
So either she picked it up from Sheridan, because all her mental barriers were down from fighting the Shadow vessel, or Kosh's surviving fragment deliberately sent her the image to help strengthen her resolve to see the fight through to the end.
As for Arthur, yes it is a very interresting campaign and very worth playing, even though the difficulty is a bit high, if I remember corretly.