The scene where he "mis-fired" shows us that if anything he is resourceful at finding where and when people are going to be. Fortune saved those pool fools not Slayers lack of skills :p

I think people over think this whole murder mystery. We know from numerous examples that Ishamael puts names on his "hitlist" as do other forsaken and even Taim. This is a method the shadow uses period. Lanfear said she was putting Asmo on the "list" so to speak. She had time between the end of tSR and the end of tFoH to do this. So it would be in no way shape or form a stretch to think that the shadows assassin would be informed of the new target...

As to people recognizing him, you have heard of a cloak yes?