Hi folks, so I'm getting my brain in gear to move from local hdd storage, to a NAS. What I'm looking to do is to buy a NAS, a couple of drives, and load it up with all my media - and for that media to be fed to a couple of consumer devices in the house like x2 Nvidia Shields, an Xbox, etc. I don't envisage any more than x2 people consuming media at the same time. I've a few questions first, if anyone would be kind enough to chime in and enlighten me

1) I'm looking at the Synology DS918+ as the NAS itself. To populate it, I'm mulling between x2 12TB Ironwolves to start with, or perhaps x4 8TB Ironwolves. Not fully decided yet, but my question relates to drive volumes. Lets say I go with x4 8TB drives...When I install the four drives, format them, and create a volume....does the NAS itself then handle that volume automatically, ie, will it see all four drives as one volume and automatically spread any files/content across that volume accordingly? Or would I have to place files/folders manually where they're supposed to go, in terms of drive a/b/c or d?
2) I'm going to need redundancy, so am considering RAID 1. This will cut my storage capacity in half I gather, as content is essentially mirrored between drives (what's on drive a, is mirrored onto drive b). How does RAID 1 work though when there's more than x2 drives? Lets say again I choose x4 drives, with a RAID 1 setup - drive a gets mirrored onto drive b, and drive c is mirrored onto drive d? Will the NAS handle all this automatically?
3) Transcoding - I've zero use for accessing the NAS from outside of the LAN, and zero need/desire to access the NAS from devices such as phones/small screens. I'm therefore wondering about transcoding. I don't want any quality loss when using the NAS versus local drives in a pc...I want full quality, every time I use it. Considering that, do I absolutely need to use transcoding? At the moment 4K content is not something I'll bother with, so consider the bandwidth needed for sending 1080p content through the LAN for max x2 people at the same time. Is this achievable with cat5e/gigabit lan ports, with no transcoding??
Feel free to educate me, because while I'm very comfortable with pc hardware/building/upgrades, etc, I'm not that clued in when it comes to networking/raid etc. Cheers folks