I'm with Bari, still confused. Which are we talking about?
1) General RPing info about various character classes, taught "in-char" by people running that type of character. This should be taught as opinion-only, but could also be a great way of learning differences between gaming systems. You could have a wonderful debate between a D&D vampire and a WhiteWolf vampire about how things work on each of their worlds. I suggest Sigil as site, or even better, one of the non-setting rooms. This doesn't need a Magi, but if you want one, let us know. :-)
2) How RPing works on ISRP. This one should probably have a Magi there to ensure that any misunderstandings aren't passed along as truth. (Even oldtimers can have entrenched misinformation, or not be completely up on the changes since
WotC.) Since this would be out of character, it needs to be held in Nexus.