the Bluesound Node 2i does NOT need to be hardwired to the router, but can get a WiFi signal on its own, and then be interconnected to my preamp?
Yes. If you have a good wifi signal at your stereo it will play hi-res just fine over wifi. A wired connection is not needed. Then you just connect the Node 2i to your preamp exactly like you connect your phono pre to it.
How do you chose the SOURCE material, please?
Download the BluOs app to your phone or a tablet from the Apple store for Apple devices or Google Play for Android devices . The app is ready to connect with and control Tidal, Qobuz, Spotify, internet radio and much more. You just open the app, select the service you want and then you can search or browse for music, it shows the album covers, the tracklist, etc. It’s all you need until you become hardcore.
If you have a decent wifi signal and can listen to cd, the sound quality will be fine. Not the ultimate, but good enough.