Mine was just historical faculty but one or two were missing (I think some of the ones not there are currently directing too many dissertations so don't get new students). It was alright. I just talked to my POI for 15 min about a theologians and then it was over. it was weird and rushed.
It might. The contact I have at BC said that he knew the historical theology faculty needed to have all their selections determined and submitted to the theology chair by Friday because he makes the calls out to the accepted students. This makes me feel like it is department wide but it is very possible it isn't. Furthermore, I am not sure that all concentrations are conducting interviews. So my short answer is-- I don't know. Best of luck.
I have been watching the thread and figured others applying to the same schools as me might be watching, so I'll give a few bits of info that may be relevant to someone.
Boston College Historical Theology department has finalized their decisions. The students who are getting offers will hear on Monday.