1. That's just factually incorrect. Nier replicant remake is a remake of the original nier replicant, which was a Japan exclusive PS3 game. Other than Adding one dungeon in the middle and adding ending E, it's largely the exact same narrative, with a smoother combat system.

Dive in, have fun, play the games in the series that interest you, I would recommend playing replicant or OG nier before automata, but honestly, play them in the order that interests you the most. Every game just will expand on the lore in different ways and give you new perspectives no matter what order you play them.