Can an Elementalist use all manifestations (Theurgy, Philosophical, and Medicinal) or only one he has the virtue for?
This question is aimed at the Elementalist hedge magic in the Hedge Magic Revised Edition book.
Only the one he has the Virtue for. If you look at the four "(Type)" Virtues on pp19-20, you will note that the second paragraph of each Virtue's description says (with the appropriate verbs for the Virtue):
This Virtue may be taken up to three times, to indicate that the character can control multiple types of elemental targets (Medicinal, Philosophical, or Theurgical). The first type chosen requires a Major Virtue, the others are Minor. Each type of Controlling must be learned separately, but all three use the same Art score, so that a character who takes this Virtue three times would have only one Controlling Art, not (Medicinal) Controlling, (Philosophical) Controlling, and (Theurgical) Controlling.
You need to purchase the Virtue separately and develop a separate skill for each of the three Manifestations.