1 dollar = 3.09 pesos so ARG 99 equals a bit less than USD 33. But green fees are often cheaper than that, about ARG 60 / USD 20.

Caddies are quite frequently used and can cost about USD 15 for 18 holes. Usually players stop some 10 minutes at the 9 hole's snack bar and pay for the caddie's lunch (sometimes a stipulated fee of not more than USD 5, that depends on the course).

Caddies don't know any English in 99 % of the cases. Perhaps some of them do at the more expensive Patagonia resorts like this one or this one (both are very beautiful places, by the way).