I'm from Rio, but you can go to Florianopolis city, at Santa Catarina state, in Brazil. A lot of Argentina people go there, because it's somewhat closer. Sao Paulo state and Rio itself have some fun waves year around, exccept in mid summer when it's a little skechty. Excpect moderate to surreal-hardcore nightlife. And moderate to surreal babes at the beach.
In Argentina I know there's some waves at the east coast, at Mar del Plata. Nothing special, and VERY cold water. If you wanna go to Argentina check for the surfing in Chile, very close and facing west, the pacific swells. The Iquique region has Very good surf. Also cold and dont excpect any beach life in those countries. On the other hand, Argentina girls are absolutelly astonishing. Take my word on that.
Bottom line is. If You wanna surf, go to Brazil. If you wanna learn spanish, go to Argentina.
About the wetsuit, I don't wanna advertise any name brands, but Brazil's Mormaii make some world class ones, and cheaper too. You won't be disapointed on those at all. But besides those, that I know from years now, I have a Billabong 3/2 fullsuit foil 50 (wich means 50% of supersterch rubber). It's just GREAT. I can't imagine what's the foil 100 like.