You have many questions. The revenent race was published in a UA article. it is playtest material, not published material. There are no official answers to these questions. If your DM is allowing the use of this playtest material in your groups campaign, then the two of you can work out these details together.
For my game Revenants are reanimated corpses. They would not have to eat, but at first they might try because they are used to it, but they would gain no satisfaction from doing so. They would not be fertile, and would rot. They would need to breath to speak, but not to survive. They would not need sleep, but would still need to long rest to regain class abilities that replenish from long rests.
But like I said, that's for my game.