(1) If any question arises in any proceedings under this Act as to the liability of any person to pay compensation (including any question as to whether a person injured is or is not a ¹[employee]) or as to the amount or duration of compensation (including any question as to the nature or extent of disablement), the question shall, in default of agreement, be settled by ²[a Commissioner].
     (2) No Civil Court shall have jurisdiction to settle, decide or deal with any question which is by or under this Act required to be settled, decided or dealt with by a Commissioner or to enforce any liability incurred under this Act.