The emphasis in on the first syllable and the ch is pronounced hard as in loch.
The original Calchas was the foremost seer among the Greeks that sacked Troy. While he is mentioned by Homer, his most important roles are chronicled elsewhere. He was responsible for informing Agemmenon that the Gods frowned on his expedition to Troy. The only way to regain favor, and the winds necessary to cross the Aegen, was a virgin sacrifice. Agemmenon sacrificed his daughter Iphigenia. Not only did this sacrifice allow the Hellenic fleet to move on its way, but it continued the tragic fate of the Atreides family.
As far as this game goes, I'm a very low intensity player, but I have a hard time stopping something once I start.