You sometimes don't... Or they come in with a delay. Comments and votes are also going missing. It's a known issue with the bigger instances, outgoing federation gets bottle-necked and starts dropping stuff. v18 improves it massively but .world hasn't updated in waiting for v18.1

Not that I can tell. It might, if you're the first to sub, but aside from then, you still get anything that makes it to your server in your feed.