As far as the Pask issue, it clearly says "No unique models may taken other than the ones listed"
But nowhere does it say Special Character are restricted to Cadian Planet, meaning if you could take Pask or Creed in a Core or Auxiliary choice you could in turn take Straken or harker in any of those formations. I feel that they included the bit about No unique Char. outside of the ones listed to prevent this argument of adding Unique Characters to non Battle Command Formations aswell as keeping it Cadian SC only.
Correct and Pask is listed under the Battle Group Command on the same page as that sentence. I'm still waiting on ITC and GW FAQ to respond.