Fascinating. They learn and remember and teach.
Sounds like an opportunity event to me; just playing around, and there was no negative blowback as far as they are concerned. So, “that was fun; let's do it again!”
Yes. As do every creature on Earth. We find it difficult to 'translate' a meow or a dog's bark. We hear the birds sing and we don't understand what they are singing.
But they understand us. Maybe not so much the words as our actions, our tone of voice, our gestures.
They understand 2 types of communication (at a minimum) and we only use 1. Who is 'smarter'? The orcas have expressed themselves to us, but we don't get it.
They used to have a deal with humans. Humans tow back a whale, and the orcas escort the hunting party and keep away the sharks. Upon safe docking, we would SHARE the food (ESPECIALLY THE tongue. They love that tongue.)
We no longer do that and they have been very patient for a long time.
Everyone reaches a limit of their tolerance, and they are doing their best to make it clear.