IIn a plaza principal, it is very likely to find different kind of buildings related to what people need as citizens and social individuals such as municipal buildings, police stations, churches or cathedrals and banks. Family homes, on the other hand, are not common and would not be found in a plaza principal.
In a plaza principal several events might take place such as meetings with friends and music festivals as opposed to corporate meetings which are usually held in private buildings, hotels or business companies.
As regards to how Diego Luna would greet their friends, the “¿qué onda?” option is the correct one as it is a common greeting in Mexico. According to Mexican customs and habits, Salma Hayek and Jennifer Lopez would greet each other with only one kiss. Kissing on the cheeks in Latin America is an accepted ritual and it might show respect, courtesy or friendship.