But do the other Drow gods not also dwell there, dispite the teachings otherwise of the Drow faith?
Yes. The other drow gods (Vhaeraun, Selvetarm, etc) make their homeplane there too. Eilistraee also has a home in Arvandor I believe with the good elven gods.
I say as close as BGI and BGII. It had some of the well-known major ideas of FR, but it didn't come to the point it was all nit-picking. In fact, in some of the FR information available contradicts itself from book to book. And in more than just spelling. So I say to use it loosely, but don't be a slave to it.