: I don't think there was ranking of leadership among all the Maiar. If any ranking of leadership did exist, I think it existed solely among those Maiar serving a specific Valar.
: I think it was more along the lines of, for example, Aule telling one the high ranking Maia that served him to have some task perfomed. That high ranking Maia might tell a Maia of lessor rank serving Aule to actually perform the task. However, a high ranking Aule Maiar could not tell a low ranking Yavanna Maiar what to do.

Thinking of these classes brought something to mind....when Gandalf said something about going to see Bombadil and "having a talk such as I haven't had in a long time" (Something like that) I wonder if he meant that the last time he spoke to Tom they were both spirit Maia? (Assuming that's what Tom was of course) if not, it was a strange comment....