A bit out of the Brazil theme, but as I'm coding Rio de la Plata and Argentina's stuff I decided I'd share with you the overall idea for feedback.
UA: Docta Latinoamericana: Whenever a citizen is born you receive an amount of Science, Culture, Production, Food or Gold depending on the City Focus. Growth rate increased during Golden Ages.
UU: Granaderos a Caballo: Replacement for Cavalry, receive the “Code of Honour” promotion, which heals half of their health points when starting a turn with less than 10 HP. (may only happen once) Take longer to produce but start with 10 more XP. (ranged attack?)
UI: Yerba Mate Plantation: May be built on Plains tiles next to fresh Water after the discovery of calendar. Grants a free source of Yerba Mate, yielding a total of +2 Food and +2 Culture aside from the plot yields. Cities with a source of Yerba Mate also grant +1 Extra Happiness.
The idea is, Yerba Mate growth to get yields, Golden Ages to grow even more and get even more yields. Granaderos to defend and conquer, yerba mate and golden ages to enhance growth in conquered cities.