Would be fine, so long as at least the person in question followed is able to see/is notified they were followed; otherwise, its a big no from me, personally

I think depending what you're viewing the site on, you'd already see any posted emojis. It would be cool for FN to have their own optional set of unique emojis/smileys though.

Would be pretty neat! Might need some privacy/filtering/etc options for users with lots of followeres

That too! Also it seems like imported GIF files import as a GIF, but don't actually have the animation going