Actually, Neal has it mostly wrong.In the pilot chapter of One Piece, Romance Dawn, Luffy's powers were still given to him by eating a gum gum fruit, but the original gum gum fruit came from an ancient tree that only bore fruit once every 50 years. Partially correct on Neal's part, but this original concept was different from the Devil Fruit we know now.The Devil Fruit in the series now, however, have no known origin. They are believed to be incarnation of the Sea Devil, a creature/monster that they haven't introduced or explained yet.There are believed to be more than 100 different types of Devil Fruit and it is has been revealed that a certain type may exist more than once, but not at the same time. Meaning that someone else in the past may have had the same Devil Fruit powers are someone in the present, but that person must be dead before that particular fruit and power will appear again.The part about only needing to take a single bite for someone to gain all the power of a Devil Fruit is correct, though. After that first bite, it no longer gives any special abilities.   See 3 other replies

Okay I have the answer that regards your other question. According to Oda-Sensei, whoever takes the first bite out of a devil fruit gets the curse.
After that, its just a weird looking fruit that tastes bad.   See 3 other replies

They all come from a specific island in the grand line and each one grows only once every 50 years, or so. I think. Yes. Interesting 2nd question I've never heard that mentioned.   See 3 other replies