Hey Jazzyvee,
Brazilian music is a beautiful combination of rhythm and harmony and I hope you have a great time with that band. I was lucky to have worked with a few Brazilian artists back in the day - Moacir Santos, Dori Caymmi, Sergio Mendes (sometimes more "pop"), and a couple times with Ivan Lins. Some of the best music I got to play.
I'll offer one pointer only because it was offered to me by Moacir when I first got into it... For the basic samba, it's all about the
2nd note. The bass player's job is to do what the surdo drum does and emphasize the (1/2 time) backbeat to keep things moving along. If you think of it in a quick 4/4, you can play a very short note on the downbeat and then a loud long note on beat 3, usually the 5 of the chord. It's slightly related to reggae in that it's not all about the downbeat.
There are probably a million great examples online so look around for a few samples. That short note, long note samba thing has stuck with me and I've found myself doing it many times in music unrelated to Brazil. HA!
Jimmy J