I'm taking about r/antimeme type.
A lot of things are accepted there, but usually, it's just when you use a well established meme template completely differently from what is expected. Could be an anti-joke/literal usage of the meme, but not always.
That would be the actual definition, yes. But many if not most people who use the word "meme" to mean "funny picture and caption" don't actually know what the word meme refers to. So they go by some definition originating from Reddit, Facebook, 4chan, etc.
Kind of. As a concept but not the definition people that use it attribute to it. The act of people getting that definition wrong is itself a memetic behavior.