I do hope that the Drow can be incorporated into the Elf heritage rather than making it a whole separate thing. But, there have been so many unique abilities attributed to make them powerful and formidable opponents, that I am not sure that a single feat would properly cover everything they have been depicted as being able to do.
You are a Drow you gain (X signs of heritage). Select two of the following benefits: Darkvision (with light blindness), Arcane Innate Spells, immunity to sleep, something like a dwarf's ancient's blood for resisting magic.
Additionally, you replace your Common racial language with Undercommon. Your starting language selection changes to: Common, [some other languages]
Special: You can select this feat twice. The second time, it loses the heritage trait and you gain the other two benefits.
Then leave Poisons to something else.