As far as what to bring besides what is on the list, there really isn't anything you need to have besides what you are supposed to bring (see Clothing List)...
The mission bag, backpacks and briefcases:
The mission secretary said that $15 should be for buying a mission bag when they get to the mission office. They didn't have that when I was there, but it sure would have made it easier... From my experience during my mission, I went through a couple of soft-sided leather type briefcases with a top that opens with a flap that attaches to the side. When I first got there, I just had a regular backpack. I still used the backpack for a couple of days, but since we weren't supposed to use them, one of the missionaries I was with gave me his old briefcase. It worked much better because it was easy to open from the top and grab things out of while I was walking or while it was sitting on the ground. Plus if there were a few Book of Mormon's in it, I could sit on it during a discussion with someone. Many times we would be talking to someone who was just outside of their house sitting in the shade on the sidewalk watching the street, and we could strike up a conversation and then sit down next to them, or in front of them on our briefcases. A hard cased briefcase would probably have been nicer, but I never had one during my mission. Half-way through my mission the old briefcase finally wore out, and so I bought another, and I got the same kind as before. I was able to carry more in that kind of briefcase than a hard-covered briefcase like what you would think a businessman might have. I could put things like Book of Mormons, pamphlets, and even clothing if necessary, like a sweater on cold months, or baptismal clothing if I needed to, stick my umbrella through the top and be ready to go. I miss those days. It was especially nice to be able to put a small umbrella inside of the briefcase, or a long umbrella through the top of it with both ends sticking out from under the flap of the briefcase top.
In short, I'd say wait to get one in Brazil, and you can decide whether you'd like the harder briefcase for the nicety of sitting on it, or the softer side briefcase for the nicety of fitting more in it.
As far as suits go, I took two. Two isn't absolutely necessary, and it would have been nice to only have to carry around one suit instead of two in my luggage, but it isn't as easy to get a well tailored suit once you are already in Brazil as it is in the USA, so eventually I was glad I had two. Most of the time, the suit jacket will only be used for meetings, and not all of the time for them. One of the best things would be to have multiple slacks that match the suit since those wear out more quickly. I had two two-pant suits, plus other slacks as well. I definitely had plenty... probably too many, but it is hard to strike a balance of how much to take.
Luggage should be small enough to easily handle everything himself for a mile if need be. I had the wheels on one of my suitcases die the first day in Brazil. I had so much extra stuff, that I spent the rest of my mission trying to leave some of it wherever I lived.
Don't bring too much!
So, you decide, but try not to pack too much. I think it would have been more useful to have $50 extra dollars to use during my first months as a missionary and take a lot less with me, than vice-versa.
When I packed my bags, my mom wanted to make sure that I had tons of stuff. She packed me an extra blanket, tons of bars of soap, office supplies, etc. They all got in my way most of the time. I ended up leaving most of it at various places on my mission. So my point is, you can get pretty much anything in Brazil that you can get here. I suggest that rather than trying to bring America with you to Brazil, instead that you let Brazil into you when you get there. In other words, become brazilian during the time that you are there and you will be able to serve the people better.
Nice small things to bring
I'm not saying that you leave everything behind, brazilians will ask you many times what your home is like, etc. But if you want to not be homesick, it is best to decide to become brazilian for a little while and enjoy the experience!
Some things that brazilians would really like you to bring would be:
1) Pictures of your home town: Show them to people when they ask, but don't spend your hours looking at them yourself.
2) Pictures of the prophet and apostles, temples, etc.: These can be great presents to people who are baptized. You can write a special message on the back for each one. Be careful though, everyone will want some, including members and other missionaries! These were the best things that I brought because they are flat and can fit in the bottom of a suitcase well. Smaller pictures are great too!
3) Other than that, maybe some maple syrup extract in case you can't get it in the city you are in. Learn to make pancakes and the syrup. Your comps will love you! You will be using a gas stove with probably a small pan. There may or may not be a spatula in your apartment, but you can always buy one downtown. I wouldn't bring it with you...
I hope that helps a little bit. Remember, you are there to represent the Lord, the more you put your heart into the work, the happier you will be!