1) Last time Emma was in the EF, she wasn’t expected to dance at a ball. This time she was. Last time Emma was in the EF, she didn’t need to blend in. This time she did. Emma’s experience in the EF this time was a lot different to her experience in the EF last time.
No she wasn’t. The dance was unnecessary to the plot of uniting Snow and Charming. It was something they did spur of the moment. It was there to make Emma feel like a princess. It wasn’t in any way shape or form necessary to the goal Hook and Emma had.
2) Hook’s knowledge of the EF is more sturdy than Emma’s for the fact that he was born and raised in a society that didn’t look like it had changed much over 200 years. As a naval officer, Hook would’ve attended formal occasions. The ball was one such occasion.
So much conjecture! We saw the EF of Hook’s time for maybe 5 mins. We saw more of it in Rumple’s past in A Desperate Soul and the Crocodile. It has DEFINITELY changed since then. And again, the actual dancing was completely unnecessary to the plot of getting Snow and Charming together. They could have done anything else and the events would have played out the same. Emma was not expected to dance.