Maztica and the Horde and Kara-Tur and Al-Qadim ARE Forgotten Realms material, but in a way they are also not Forgotten Realms material, I guess. The Horde (via wars with Cormyr, etc.) and Maztica (via sending of Helm's watchers there) have a bit more connection, I guess.
The Draconomicon, Drow of the Underdark, Sea of Fallen Stars, etc. are all basically just part of the Forgotten Realms campaign, I would say (they are more expansions than new campaign settings). They are also geographically located close to other typical FR locations as well. So I think that anything in these expansions would be game as well (but not the previously mentioned Maztica, etc.).
Arcane Age is a bit more iffy, as it is another time era; it is definitely FR, but it is a quite different campaign and not easy to visit (since you need to time travel)! So I would leave this one out.
But I like all your suggestions for things we need
(Forgot databases, that is a big one...)