Home Theater / Media Server hardware questions

Greetings all,
I have been researching on and off the possibility of creating a small home server for data, media, and other files which I presently have spread out over multiple HDD's lying around.

I expect at max 3-5 devices may access data simultaneously, in a worst case scenario, all some sort of HD Video (no 4k yet). I do run Wireless AC dual band which I feel should be sufficient from a network standpoint.
Does this require a decent amount of CPU power to feed all these devices? I am thinking 35w Intel i5 or i7, AMD probably does not offer something so efficient.
Do GPU's play any role in these servers, and if they do, is that dependent upon the server's OS? I imagine the video rendering is all handled on the client end? (unless I use this as a permanent TV PC)
Is a single HDD sufficient to feed all the devices or would it require raid? (I see this as a power and additional HDD cost)
About how many TB of HDD space does the "average" person use, 2-4TB? I know some HD videos/captures I have are on the order of 100's of GB's. I have a couple 5400rpm 5tb drives hanging around, so I could either use one 5tb and the second as a backup or buy more and run 2 for a total of 10tb with 2 back ups.
Maybe I should just continue with Ext. HDD for video capture as this alone could potentially run 5tb by itself.

I would be considering a low power, quiet, fanless build. Fanless PSU's are available, but given the efficiency inherent to PSU's within a given load range, 50-80% roughly? Is there any benefit to getting one since most are of the 400w range and I would not be drawing anywhere near that? or is a lower wattage fan PSU cheaper in electricity?

If you have some good "modern" links to home media server information feel free to share them. But my experience has been the specific information is generally spread out over a variety of forums, and it is usually more efficient to ask the experts.

 

I have a 16TB server, and a 44TB server at my other house. Both of them are running Windows 7. I use MediaBrowser3(Emby) to handle all of my movies. I can stream to a PC, Android, iOS, Roku, Chromecast, raspberry pi, ect. via Wifi or Lan, pretty much any device that play movies.

How it streams depends on the device accessing the data, if I stream from my server to another PC then it will do 'Direct Play' which means the server isn't doing any processing. If I stream to my cellphone then the server's CPU will automatically trans-code the file as it plays. You can adjust your bandwidth settings, transcode setting on both the phone and the server.

If you don't want to RAID all of your drives you can do a virtual drive array(my 16TB server is setup like this). I personally use Drivepool. This basically combines all of my drives into a single drive. If you have random drives kicking around I would probably go with this route as you're drive sizes don't have to be the same.

If you are going for redundancy you can also do that with Drivepool, you can tell it to put a specific folder on x amount hdd's at all times so if one dies you still have your information, I have my redundant folder set to 4 hdd's.

My 16TB server is just running a i3-4130T and 4GB of RAM. GPU's can play a roll in a server, if its optimized to transcode for you, which Emby can do for specific Codecs if you get into it enough, I haven't tried it though.