+5 Yes, Puerto Rico is widely considered a colony—or often described as the world's oldest colony—due to its status as an unincorporated U.S. territory. While residents are U.S. citizens, they lack voting representation in Congress, cannot vote for president,
Well, the minimum of main culture aspects being supporting the democracy, a certain amount of tolerance for others with different opinion and looks, rule of law. "well integrated subculture" meaning people joining an already exisiting main culture in different ways, like immigrants and not being openly hostile to people with other opinions or looks who stem from other subcultures/backgrounds without proper reason. An indication of a failed integration are parallel societies within one country.
Yes, I would agree with you that polite, nonviolent and maybe even friendly interaction is positive. The main culture aspect or fundamental understanding of the US society is problematic these days. One could even argue whether it's still exists. However, since there are many people who fight for it, you could at least argue that the idea still exists.
"we would be far poorer without the contributions from other cultures" Very much debatable. There are so many positive AND negative aspects of it. People from the ends of the political spectrum see it in a contrasting manner. Pro-immigration people will biased towards positivity á la "enrichment" while contra-immigration people will be biased towards negativity á la "criminals and rapists". The truth is somewhere in between - both things can be true at the same time, often depending on the individuals and group dynamics. It's complex.
The part about the food is very much true. The same thing is true for Turkish and Middle-Eastern food here in Germany and I very much enjoy it. An argument against it would be illegal immigration, human and drug trafficking, narco organizations, wage competition, wages without taxation and so on. On the other hand, you have great workers who value education for their kids, have good food, are sometimes lovely people, support the wobbly demographics and so on. I think we can all agree that your president and ICE are not a good solution for any of this though. It was never meant to be one.