Combat Commander gets your blood flowing.
From the summary table at the back of rulebook, it says that "The Player for the Busho who was activated immediately preceding Orders Phase may attempt a Momentum die roll to give that Busho another Orders Phase (C ) or Samurai Phase (D). If not go to F.
From the rules of Momentum (5.41), it says, "At the conclusion of an Orders Phase, if the Busho who had issued Orders for that Phase is not Finished, and was not previously Trumped, the player may attempt to undertake an additional Orders Phase with that same Busho."
(A) May the player only try for Momentum if the Busho previously used Samurai Phase (not Orders Phase)?
(B) May the Momentum Busho take Samurai Phase, or only Orders Phase? The summary table and rules are inconsistent.
I can see why you are confused. This is typical for Berg rule sets.
I believe the answers to both your questions are No.