Initiates or Trainees are probably pregrad Inquisitors.  Initiate if Acolyte is a training position, otherwise it should be used for the church and trainee should be used for the Inquisition.

Bishop is a [i]skill[/i] position.  perhaps a middle skill rank could be ...iunno, deacon?  I like that.  ^.^;;

Inquisitorial Command/Officer ranks:

-top guy.  Just one.
Lord High Inquisitor?  Supreme General?  Commander in Chief?  probably something along the lines of the latter two, since technically they have command of the secular army too, if they want it.

-second rank, only a few
High Inquisitor

other ranks:
Master Inquisitor
Knight Master Inquisitor
Knight Inquisitor\

(functions like lieutenant, lieutenant commander, and commander)

Teachers are probably taken from these three ranks.  Maybe just the knights and knight masters.