When reading about Captain Eden, the first actress that came to my mind was Viola Davis. But when her age was mentioned, I thought of Angela Bassett. Though when I saw Gina Torres on Flash Forward, I thought she would make a nice Eden as well.
As for Batiste, though he doesn't fit the description at all, an image of Delroy Lindo popped into my head and stayed there.
For Gwyn, I see Alaina Huffman (Medic from Stargate Universe)
I also saw Hugh Laurie for Cambridge.