As a latino, I think that specific knowledge that locals don't expect from tourists (like local history, culture, geography) it's always a good surprise.

it depends on what part of Latin America but I think that if you could sing and dance our music or at least if you try to do it, that would be interesting, trust me haha and if you try to speak spanish,( we love when foreings try to speak spanish) and I don't know show us what your culture is like, that's the most important thing you can do to impress us. :)

I Don't know. All people get impressed by different things. Don't try too hard and just be yourself.