Maybe you can start by explaining what primo means to you in English?
You can say anything you want to Primo.
COUSIN
Spanish is relatively the same but ricans say gracia w/o the s at the end and primo is cousin so its gracia primo .
Roberto es nuestro primo = Roberto is our cousin
primo maggio
primo Juan
hola primo
De tu primo(a)
You can say anything you want to him.
you can say anything it depend how you feel and you feel about him
You could say "¿Conoces a mi primo?"
Gracias primo.