Answer 1: @CrystalGipsy has got you covered on that answer. I’m pretty sure sending and receiving to an AirPlay device simultaneously isn’t supported by AirPlay.
Streaming audio to the Apple TV from Roon will use the AirPlay protocol not RATT.
The Apple TV isn’t RoonReady (RATT) capable.
Answer 2: The transfer feature isn’t in the app - I’d have to check if it’s available via the Roon API. I think it is…