Yes according to [0]. Just look at their campus map [1]. It is massive and some of those buildings are dozens of stories tall.

[0]: https://www.amazon.com/p/feature/4kc8ovgnyf996yn

[1]: https://static.seattletimes.com/wp-content/uploads/2017/09/7...

It doesn't really, maybe by footprint on the ground, but Amazon has lots of tall buildings.

Yes they do, and the math works out. About 8k people work in their two belltown towers alone.