I’m not sure if this is new, but when I clicked on the /r/pics protest post link from the frontpage here, I was redirected to this: https://old.reddit.com/premium
I’m not sure if this is well-known or not that they’re pushing it now, but it’s the first time I’ve seen it, especially on old.reddit.
You can. For email, DNS serves a similar purpose to the telcos’ mobile number portability databases. If you want to move your email domain to a new server, you just need to update its DNS MX record.