Hi Tom,
Great to have you on board with Roon, hopefully your music discovery concerns might be over ! As to your questions:
Meridian devices best answer that description at the moment. AirPlay devices are also currently supported as network zones, but have the limitations of the AirPlay protocol. There will be many more integrated devices after release of the Roon Advanced Audio Transport (RAAT) SDK to manufacturers when firmware will be written for existing devices to become RoonReady.
Squeezebox and Raspberry Pi support are also intended with RoonSpeakers in the next major release, which is aimed for November.
Playlists written in Roon do not currently sync back to Tidal, because they may contain local content not in the Tidal library.
There is not yet a “mobile solution” for Roon. Some users have used VPN to establish long distance network connections to their Core, but bandwidth limitations are likely to prevent that being viable for mobile devices.
It is possible to Focus on, say Top 25 played tracks, save it as a bookmark and Play all with shuffle on. Roon has a lot of it’s smarts in Focus searches. Playlists consist of specified tracks, rather than a Focus search. You could use the bookmarked Focus search to create different playlists at different times as the relevant tracks change.
Edit: I’ve shifted your post to Roon Software, where it will attract more general discussion than in Support.
Cheers,
Andybob