New users is not a good metric. Many people will create accounts just to check it out even if they dont stay.
I’ve made multiple Lemmy accounts on different servers.

Dunno m8. From what I’ve read it’s best to leave it undetermined.

#4 is the language.

Same. Bots are spam.

This is why, to me, it makes sense for instances to be topic-focused.

Imagine a Mine.Craft instance with communities of various aspects of the game.