Do the souls have access to faster than light travel and communication? I don't think so, since it takes many decades or centuries for the souls to travel from one planet to another. When discussing where to send the seeker, Wanda dissuades against sending her to the seaweed planet, which is located in the closest stellar system, and it takes only a decade to go there and back. This fits our closest star, Alpha Centauri, which is 4.3 light years away, assuming that they travel near, but not faster than light. Also, since Wanda talks about going there and back, it seems that they don't have faster than light communication either, because then, it would take less than a decade for the souls on the Earth to receive the information that the seeker was extracted from her host and sent away.
On the other hand, it seems that Wanda has information about the current status of the other planets, in particular the recently colonized dolphin planet, not the status decades or centuries ago, and likewise for souls on other planets. Otherwise, since the colonization of the Earth begun just about a decade ago or so, the souls on most of the other planets can't know that the Earth has been colonized.
In particular, Wanda, while still on the seaweed planet, heard rumors about souls which had difficulties to control their hosts on the Earth. If the souls have no faster than light communication and travel, this must have happened in the very beginning of the colonization of the Earth, since otherwise, there was not time enough for this information to reach the seaweed planet and then for Wanda to go to the Earth. But it seems unlikely that this should have happened and the information about it being spread in the beginning of the colonization.
So, it doesn't seem to add up...