Just simple advice (this goes for all RPGs).
If your running the game for the first time and the players playing the game for the first time too. Then just use the designated core book/books (core races, core classes, core rules), simply put play Vanilla first. And only after that start house ruling stuff and allowing additional books.
This advice goes for every RPG. Just imagine allowing Vampires and AI and stuff like that in you first ever session of a game that you and the players just started playing. XD
