As for Cassandra, I don't think that she would be a hardliner and put a heathen at the helm of an organization. I think the different racial backgrounds of the protagonist would necessitate that. Since I have a strong feeling that Cassandra will be the one companion who will remain at the side of the Inquisitor no matter what, I imagine she would be less of a hardliner the more traditional Andrastians. Although Leliana or Cullen may be another matter (depending on which direction their character arc has gone in), particularly the latter.
That's a good point. If you have characters who have more extreme views, you don't want them to be the ones the PC meets first and then has to have along for the rest of the story.
You generally want them like Bethany or Varric in that they come off as moderate and generally supportive of the PC.
Well, I despise Javik and consider Shale a waste of space, so I'm not too saddened by any such loss. The angry growly antimage niche is already filled by Fenris.
You consider Sebastian a better character than Javik or Shale?
And Fenris is neither pro-slavery nor pro-Exalted March. I don't recall him saying much if anything about his faith.