Forgotten sentences

1. When you're in a relationship, it's important that your personalities match.

Or

When you're in a relationship, it's important that your personality matches.

ARe both useable and what's the correct way of saying it?

2. My friend talking to me about my visit to NY. They say in real time:

Have fun and let me know what you've enjoyed. - THis sounds strange please tell me what's wrong w/ it.

And

Have fun and let me know what you end up doing. OR

Have fun and let me know what you ended up doing.

3. My friends are taking the subway to an area nearby NYU. And I say: What are you guys doing at NYU? Or

What's fun around NYU? Or

What's going on at NYU?

Are all three useable? ARe there any more different sayings? Thanks!
Thank you!