Your fiancé is going to need a CPF to work legally in Brazil.  How on earth are you going to arrange for one?  Without a CPF, I assume that he will be working and paid "sob o pano".  Won´t this mean that he will be in Brazil with a 90 day visa and the requirement to exit and return every three months?   

I strongly recommend that, if he has taken one, he bring with him written proof he has taken a defensive driving class in the USA.  It will save him money in Brazil.  He should bring his US driving license, of course.  DETRAN may tell him that he needs to pay around R$800-850 for a carteira de habilitação.  Don´t believe it.  He should be able to get one for around R$150-160.  It´s a matter of finding a bureaucrat who will get off his butt and research the law as it applies to foreigners.

If there is any possibility that he will be wiring money to Brazil from an account in the USA, do the necessary paperwork while still in the USA.  The Bank of America, for example, insists that transfers be set up in person in the USA.  Customers are then given a telephone number to call in the USA, a code, etc.  The account in Brazil could be in your name.

Put him in touch with Americans living in Brazil.  He is going to have problems that can be avoided easily by using the experiences of others in the same boat.  If he uses "VISA Plus", for example, he should be aware that the Banco do Brasil usually has at least one machine with access to the "VISA Plus" system, but that machine will not be marked and there will probably be nothing posted in the bank to indicate that the bank has access to "VISA Plus".  The DETRAN "burrocracia" mentioned above is another example.  Make sure he understands the importance of keeping a written record of any "protocolo" information he is given.  As an American, he is not going to attach importance to it, mistakenly believing that anything that goes into a computer can easily be retrieved from a computer.  Not true.  Keep the numbers, keep the names, keep the dates...keep everything. 

I learned the hard way to protect my US ATM card.  I once carried it unprotected in a moneybelt-type device.  Guess what happened when I accidentally bent the card?  Yeah, I couldn´t use it to withdraw money and I had to replace it.  What did I do for funds while awaiting the replacement?  I still carry the US ATM card in a moneybelt-type device, but...it is now carried inside an aluminum business card case (easily found at tobacco stores for around R$15-25). 

There are lots of little things that he will need to learn.  Having you at his side is going to be a big help.  It´s rough to learn things on your own.

Good luck.