Some more updates I need feedback.
Internet
To access the internet seems the best way would be with Airport Extreme Base Station.
Then to connect every stationary Mac computers via hard wire throughout the house. If you cannot hard wire use a powerline ethernet solution to ensure a fast, safer and reliable connection.
*Because this uses the Airport Extreme Base station you are limited to having 3 hard wired devices. Choose wisely.
**Unless you use a different router with more gigE ports or use a switch.
Entertainment
Either
A Mac mini with plex to stream all your content to your TV. Perhaps add a bluray player to the mini if necessary.
The mini also offers the flexibility of the internet, applications and a DVD drive.
OR
Get an Apple TV and a DVD/Bluray player.
Speakers: Whatever tickles your fancy
Receiver: Something air play enabled to be able to play content from iOS devices anywhere.
Remote: either the Apple remote or an iPad to control your home entertainment system As long as the app you use supports all your devices.
Backup
I would use either a Synology DS410 because it is not hardware specific and flexible. Connect it to the Airport base station to backup every computer on the network and the media collection. Configure a FTP and download server as well as backup.
I could also build a server from old computer parts. (in my case this would be cheaper as I already have the parts)
Networking
As mentioned before all desktop/server/NAS/ATV2 will be hard wired to offer reliability and safety. All devices will be on the same network. I would also disable the guest network in the event I have guest over that would need to use it. I won't share my WPA2 key with anyone.
Did I miss something?