Thing is the way it works is, it only federated content from communities an account is subscribed to on that instance. Since there’s only my account, my all is like my subscribed. So it’s pretty empty.
It depends. Lemmy gives you pretty fine control if you put in the effort.
My home instance lemm.ee for example does not cache images from other instances, so any abusive material posted stays there even if viewed by a member of our instance.