Very interesting! Although I would rather have seen some of the table of contents concerning the Bestiary, this is quite intriguing as well!
Likely. However, given the sheer number of elven deities (we're at like 19-20, if we include the FR-specific drow gods, Eberron's Vulkoor, and Ghaunadaur), that will take up quite a lot of space.
Yeah, but while (surprisingly) all the Dark Seldarine get a write-up, only a handful of the Seldarine do (their write-ups seem to be more in-depth, tho, while those for the Dark Seldarine are much more superficial. Idk why they made this choice, there's at least as much lore about the drow gods as there is about the elven ones. Whatever, I guess...).
Perhaps because those Seldarine Gods are the most broadly useful for Players, although some Dark Seldarine Gods do have none Drow worshippers too.
The only drow god that falls in that category is Selvetarm, that I know. Eilistraee, Vhaeraun, Zinzerena, Ghaunadaur--all of those do their own thing.
That is just what She wants them to think. If She wanted to micromanage other gods, she would be LE not CE.