For informal situations most people greet each other with kisses on the cheek. Depending on the region in Brazil, the number of kisses varies. In São Paulo one kiss is enough, in Rio de Janeiro two kisses are the norm and in Minas Gerais you can´t get away with less than three kisses!!!|
But if you don´t feel confortable with kissing, you might get away by just waving your hand or shakin hands.
Drinking is allowed in public, you can drink at the beach, in parks and even on the street if you want. But don´t drink and drive!!!
Also, drinking is legal for those 18 and over, although usually not enforced.