The Hellfire would work just like a fire ball, it's just that only he can put it out, and it's much hotter. Also he would rarely use it though cause he will take on nearly full demonic appearance in a very short time, so like after two times...you know what he is. This would also mean that he could do little else afterwards with out losing control. So it's power full, but for the most part the cost isn't worth it and is reserved for dire situations, not even his own life being in danger, Pretty much some one else s life would have to be in danger.

 As for the commune it could still serve some purpose.  mostly what we see would be like minions. But more powerful demons would be sentient and Since it wasn't explained to well I kind of guessed there there is some form of system, every army has to has its Sargents, lieutenant, generals and I'm assuming some lord that rules over them all. He him self would fall some where in the Sargent-lieutenant range. That is just how I would do it at least, but this is y'alls rp so up to you. Also hope I don't come off as pretentious or anything. That was just kind of the picture I had in my head when writing him up.