Sharing files isn't that hard. I'm using Win10 pro so it's as simple as right clicking a folder, selecting properties, selecting the Sharing tab, clicking the share button. Then select the user and the rights they have. Since it's just media files over a local network I usually select "everyone" but only give them read only permissions.
I use to give read/write permissions but I've accidentally deleted files using the trackpad on the wireless (fat fingers). I figured read only is fine.
The added plus side to this method is I also have a monitor and computer in the bedroom (I'm an insomniac). From there I can access the same shared files on the "media server" computer.
To find the files on the network, open Run and put \name-of-computer and hit enter. A list of the shared directories will open and you can map these (right click and you'll see the menu option) so they show up in "my computer".
The only other thing you might have to deal with is the firewall in Windows. But there is a pretty easy option to allow file sharing in the local network.
And yeah, you need the right space for a projector. Start with an appropriate size monitor and upgrade as needed.
Also, the Win10 computer I'm using in the living room and bedroom are just really basic computers. They don't need much power since they're only playing movie and music files and sometimes a browser. You can find Lenovo ThinkCentre computers for dirt cheap and they're tiny. These work really well.
My media server computer is actually one of my older desktop PCs with a hardware raid card and a bunch of drives in RAID1 array. RAID 1 is two drives mirrored so if one fails you don't lose anything. I've been collecting moving and music files for 20+ years so I figured it was nice to have a little redundancy on my collection. But you could use anything and upgrade over time.
Hang the pizza flag upside down just to make the point clear.