Newbie question here (since I'm renovating my house):

The situation:
3-4 different TVs with different TV boxes (some not even able to install Kodi/apps), Apple TV, iPads, iPhones, Samsung tablet, Sonos wants to share one single NAS with every media on it. For those that can be done with wire, there will be Ethernet. If not, wireless for the portables.

1) What is the best way to do it? Plex or Kodi?
2) Some are suggesting Plex back-end and Kodi front-end, what does that mean?
3) Need to be used by older generation, must be plug-n-play.
4) Hopefully streaming, illegal or legal otherwise.
5) Hopefully streaming live won't tax on the NAS (not self-build, consumer product)