

Yes and no, its an official release, but basically these are “We think this issue is resolved or this new feature is ready”. The GrapheneOS team does a gradual rollout to prevent causing people issues (since people literally can live out of their phones).
Alpha channel users get it, if they don’t notice any issues roll it out to beta channel users, if no issues found in the wider beta users, roll out to stable.
Basically it prevents a bug from being pushed out to everyone and causing headaches for the devs. You can’t know everyone’s use case so by having a smaller number of users who are expecting breakage you can find bugs or showstoppers early before it lands on a more nontechnical users device.
Yes.