Yes, you can use Tidal connect on a T2. I use it with my T2 all the time. Be sure to get the latest firmware (Tidal Connect was added last summer. Free).
Lumin app is the same for all Lumin models. Usable but meh.
Remember, that using Tidal Connect or the Lumin app, the device streams from Tidal directly. In the Tidal Connect case, the playlists that are queued to the device from Tidal’s app directly. In neither case is the app involved in receiving or processing the stream.
Yes, the SBooster is worth it. I own one and found the difference significant.