Love the Anson Mount pick For Tell Sackett. Excellent choice, I loved him in 'Hell On Wheels'. He's also a very good historian, story teller and critic on film....
I also love the idea for Cap Roundtree being Sam Elliott. ( I think he would relish that role..
As far as the others, don't know to much about them, except for Ethan Hawke ( good Choice)
I'll check out a few, then I'll be back.

Blainemcqueen