Multi-room (Android TV / Airplay-2 / NL)

I’m still trying to figure out how i can combine the various different streaming and multi-room offers in my home:

1) Assuming i start to play music on my beosound1gen2 using the buttons on top of the speaker: can i join other airplay-2 devices? or only NL?

2) How do things go together with androidtv? can i stream from it to b&o speakers wireless? would this work with airplay-2 (directly from android 2)? or via bluetooth in stereo pair? only with NL speakers or also with beolabs somehow?

3) When streaming from android tv to b&o speakers, will video and audio be in-sync when going multi-room? if so, what protocol?

4) when using bluetooth, what b&o speakers support stereo pairing? if i stream via bluetooth, can i still join other speakers via airplay-2 or NL?

Thanks for your help!