Yes on all accounts.
[email protected] is the Android community on the whatever.com server.
They are generally called 'communities' on Lemmy, I believe they are called 'magazines' on Kbin.
The instance you are logged in to won't show the @whatever.com if it has an Android community.
This would be nice to run on my home server to monitor my Lemmy instance in the cloud. It would also be nice to be able to check some Lemmy stats as well as general server stats. I'm not a grafana or Prometheus expert though.
I would like it, even if just for my instance. There are some subreddits that I liked, but I won't go back to reddit now.
Occasionally.
I created my own instance so that I know it will not just "go away".
Edit: I have a feeling that a lot of instances, besides the big ones, will vanish after the newness wears off.
It depends on what the rules are. I think there needs to be a clear cut policy on content.