Yes, It's very crowded, often 4 rows deep.
Before the feeding, let your kid(s) push their way to the wall, while you wait at the window for food. If you get there during a feeding, buy the food, and just wait for others to run out. They'll eventually move and you'll push your way forward.
What are the dolphins saying? I think they're talking about who has the fish. They know who is holding a cup, and only swim to that person. They smile at you, swim up, make some noise, and sit in front of the person with the fish while people pet them. Then they swim away, circle, and do it again. And like another has said, once you run out of fish, they have no interest in you.