So I'm looking into building an unRAID NAS sometime in the near future but I don't quite have the funds to buy the full system yet. Since I want to use my NAS to collect all my parents DVDs and Blu-rays though (If you're with the FBI: I'm totally not going to do this), I thought I could already start ripping some disks. However, I don't have the capacity to do so until I buy the HDDs for my NAS (WD Red 3TB, if you're interested), so my plan was to buy the drives beforehand, then format them into the correct file system for unRAID (can Windows even detect that?), copy some of my media onto it, then add those and a few other drives to an array once I can afford to build the actual NAS. Would this be possible? Or do the drives have to be formatted to be added to a new array even when they're in the correct file system.
TLDR: Do drives have to be formatted before being added to a new array, even if they're in the correct file system? Also, what file system does unRAID use?
Bonus question: Is the Intel Atom (formerly Avoton) C2550 with 8GB DDR3 suitable for a NAS with a Plex Server?