Went to Rio with some friends 7 or 8 years ago .... we used a firm called BrazilNuts, which now has a website. Stayed at the Rio Othon Palace, which was very nice, on Copacabana. A tour guide met us at the airport, took us on a half-day tour of the city the second day, then picked us up and took us back to the airport a week later at the end of our trip. We paid him extra one night to take us to a Samba School. One word about dining: don't go early. Twice we went to dinner at 7 p.m. and were the only people in the restaurant. Cariocas eat late ... the city starts hopping after 10 p.m.
We didn't have any trouble with crime, but we didn't go looking for trouble. Our tour guide advised us to never go on the beach at night, and to not even walk on the beach side of the street at night. We stayed in well-lit areas and felt safe.
None of the three of us spoke Portuguese, but we had very little trouble.
Have a good trip!