SonosOne (Gen 1) – Voice Controlled Smart Speaker with Amazon Alexa Built-in (White)

Does the sonos one pair up with a sonos play1 as a stereo pair?

Is the quality of the "sonos one" sound the same as the "sonos play:1"?

so I should be able to play sonos across all sonos speakers with a voice command, or play across all speakers with echo right?

Do i need an alexa device or will this sonos one device allow me to begin using alexa?