some thoughts:
Karrin - Katee Sackhoff (if you've only seen her in BSG you may not agree, watch her Bionic Woman spots or The Sentinel).
Eb McCoy - Brendan Gleeson (28 Days Later, Harry Potter films)
Morgan - Mel Gibson (Braveheart, We Were Soldiers)
Luccio 2.0 - Jessica Biel (Texas Chainsaw Massacre, London)
Michael - Josh Holloway (Lost) or Viggo Mortensen (The Lord of the Rings, A History of Violence)
Butters - Simon Pegg (Star Trek, Shaun of the Dead) or Butters from South Park, you decide.
Marcone - Bill Duke (I know he does not fit the physical description at ALL, but something about the way James Marsters reads Marcone, makes me picture a soft-talking Bill Duke).
Erlking or maybe Kincaid - Alexander Skarsgard (True Blood, Generation Kill)
Sadly, I can think of no actor qualified to play Harry in all respects, so here's a list of some that work for different reasons: James Marsters. No way can he hit the height mark at 5'9", but he kills the soul and voice of Harry. Joe Flanigan from Stargate: Atlantis may have some of the looks/attitude down, but probably not the acting chops or the light-hearted side of Harry.