Sure on the DC question!

On Dalen having cover, just so we're on the same page, Dalen is getting cover due to the corner of the house that the guard #1 is currently standing next to, right?
From either of the guard's two southern corners I don't think he has anything blocking line of sight to any of Dalen's corners, save for the blue square in the wall - which is supposed to be a window and probably doesn't extend out into the alleyway like it does on the map - that was a drawing bad.