How can this question be asked without any background information? Further, why is it being asked? As writers, your book is your sandbox. What part of this question requires outside opinion? Everything on that list can be attributed to YOUR elves as YOU see fit. All these questions serve is a validation of outside influence. These tend to serve as roadblocks to creativity rather than aid in its progression.
A comprehensive textbook on the geography, geology, wildlife, culture and history of that alternate Earth. Doing that first would make the settings of the stories more believable.
Good luck with the endevor. Tolkien tried it and he didn't succeed in the 25 years he spend on world building, which incidently is part of the reason he never published the Silmarillion.