Access is not a problem, but outside National or State Parks, land is private. Don't damage fences and close all farm gates back after you pass. Rio is worse, because the poorer districts are near downtown, in hill slopes around Copacabana, Ipanema, Leblon and Barra da Tijuca, the best beach districts. The other towns are much safer. Alcohol consumption is free, even for teens.
Beer is a national drink, along with cacha a, a very strong spirit made from sugar cane.
But they're seldom related to crime. Other annoyances include people trying to get advantage of a foreigner, but this is not so frequent, even in the big cities. Be smart, and you'll be safe. Insects can be a problem in the Sea Range and in some other coast towns not mentioned here. If one plans to stay for some days in these areas, it's better to have some insect repellent, easy to find in any pharmacy or big supermarket in almost any town.