Requesting ideas and suggestions for Brazil in 2014

I plan on going to Brazil for the WC, barring an internship opportunity that I can't pass up (will be my final summer if in grad school next year). Brief background-- have only been out of the country once, to Cozumel for one day on a senior cruise. I took Latin in HS instead of Spanish and of course know zero Portuguese.

Since this board is chock full of worldly, cultured globetrotters I thought I might be able to get some ideas from y'all. I've never done international volunteer work before, but think it would be a cool experience to do that this summer as well. I was thinking I could possibly try to learn basic Portuguese and teach English somewhere. Maybe do some conservation work in the Amazon region? What suggestions would y'all have?

FWIW, I'm in touch with a college kid whose dad is renting out a room in their house right across the bay from Rio (seems legit, I know).