NAS stands for Network Aware Server. It is a hard drive that connects to your network through the router, just like a network printer.
In the same manner that every computer on your "home network" or INTRA-Net can print to one Network Printer, those same computers can share files centrally on the Network Aware Server.
The learning curve isn't difficult at all, it's just not the same as each computer having its own usb printer or usb external hard drive. To use a network printer, each computer needs a driver that sets printing services to send the job to the network printer.
To use a Network Aware Server, you would access its web based setup from a computer, and in the NAS's setup allow it to share with only the computers you want.
NAS drives can be set up in a couple of different patterns. RAID stands for Redundant Array of Inexpensive Drives. RAID 1 would have two drives in the same enclosure running as mirrors. If one drive dies, the other still has a copy of the data. So an NAS with two 1 terabyte drives has an effective size of 1 terabyte.
Another RAID pattern you could chose is called Spanning, the data is spanned across both drives, no mirror image. Another term for that is JBOD (just a bunch of drives). In that scenario, two 1 Tb drives equals a 2 TB NAS. The disadvantage there is that if data is lost on one of the two drives, none of the data can be accessed from even the survivor. RAID 1 is safer in my opinion.
I just purchased the SONOS Connect and love it. I can access the NAS from either a smartphone or tablet, which are quieter and easier to use than a laptop or desktop computer. The SONOS has two kinds of outputs, digital into your own DAC, or analog (L/R) into your preamp's aux in
If you think about it, the NAS and Network server makes sense, especially down the road. The sound is very good, and if you have a computer on a router, why not take advantage of the infrastructure that already exists. There's no need to own more than one printer for the same reason.