I replied to the OP via email, but thought I'd post it here as well in hopes of helping others:
Hi there! (I don't know your first name as you didn't include it in your email to me.)
First, thanks for checking out my blog. Bookmark it and check it often (or sign up for the automatic email subscription) as it might help you get a feeling for life here in Brazil.
So, let's see if I can tackle your questions as best as I can. A lot of this will come as generalizations and of course, your personal experiences may vary. Some things work out nice and easy for some, while it turns into a frustrating nightmare for other people.
-Fitting in, culturally speaking. But I do consider myself a very open person when it comes to new cultures:
In Brazil, there are people of all shapes, colors and styles. You might not draw any attention to yourself as a "gringo" (foreigner) based on your looks, but the minute you open your mouth it will be obvious. And that's even after you're already comfortable with speaking Portuguese in public. You will have an accent, you will say things incorrectly -- it's just the way it is. If you're comfortable with YOURSELF, and don't care what other people think of you, then you will be fine. As long as you make the attempt to speak the language, don't come off as the typical "snotty American" and look down your nose at everything, then people here will accept you. Try not to make too many comparisons between the two places, because even if it's just an observation, it can come off as a complaint or insulting to Brazilians. Most of them are well aware that Brazil is going through growing-pains and trying to catch up to places like the US and Europe and so they pride themselves on these accomplishments, regardless of how small or insignificant it may seem to outsiders.
-The job risks involved. Currently I have a good paying job and a comfortable lifestyle:
I left the US with the same -- good paying job with long-term stability and a comfortable lifestyle. It was very hard to walk away from it and come here with no job. I already knew that the salary range for my career track in Brazil is considerably less than what I was making in the US. But, there are some things to take into consideration. The cost of living here is pretty cheap in comparisson to the US. Food/groceries, power, gas, water, telephone/internet are very cheap. The biggest expenses are buying a vehicle and major electronics. Don't be alarmed when you get here and a 1999 Honda Civic costs R$13,000... It's just the way it is. You say you have an engineering degree. There are a lot of engineering firms near Campinas, SP. But, the biggest hurdles for you (and for me at the moment) is unless you get hired by a foreign company here (US, European) that will accept someone with very little Portuguese fluency, it's going to be tough. There are a lot of local companies here that want to hire people with English fluency because they are dealing with a lot of US and European companies. In my case, AT&T has a location here and we've interviewed. They need English speakers (I'm an IT Professional) to talk with the people back in the States. The only problem for me at that moment was that I don't have my work permit yet. When I do get it, they're ready to hire me. In the meantime, I'm living off my wife's salary, tapping into some savings, teaching private English classes and doing computer work on the side. Not big bucks by any means, but like I said, it doesn't take a lot of money to live here. The bills are paid, we can save and still have money to spend on entertainment.
-Having the patience to deal with Brazilian ways:
Man, this is something that even to this day has my head spinning. I'm mostly talking about the beauracracy here. When you begin the process to get your permanent resident visa, work permit, national ID card, etc. it's a real pain in the ass. And this is even after I did my homework, got all of my documents in order, etc. BEFORE I left the US. Once here, it was always something new, and nobody had any answers or ways to help. The Brazilian system is confusing, inefficient and constantly changing without notice. Come with lots of patience or you will go crazy. You'll get through it all, but some days you'll want to throw in the towel. Once again, your mileage may vary.
-The many many challenges I will face:
The biggest challenges you'll face will be learning the language and getting the PR Visa. Both are doable, but with patience. Another thing I can think of would be driving here. If you'll have access to a vehicle, it's almost guaranteed to be a manual transmission. Automatics are only for the rich here...

Hopefully, you already know how to drive stick. And trust me, you do NOT want to wait to get here to start learning on the roads! Stop signs are just suggestions. My wife, after living in the US for 4 years, came back for her father's funeral and was driving. She stopped at a stop sign (like we do in the US -- complete stop) and the person behind her hit her. He actually got out and yelled at her for stopping. In front of the stop sign. As if she was responsible for the accident. Yeah, you really need to be on your toes here.
Now, on to the rest of your email...
So your girlfriend came back to Brazil after living in the US illegaly. It sounds like she was deported due to having the 10 year restriction. That can make things harder for the future if you decide you want to both live in the US, but you say you have a lawyer working on this so I'll leave that up to him/her. I'm assuming you'll be coming here on a tourist visa, which means you can stay for 90 days with the possibility of extending it to 180. Your email says that by the end of 6 months you'll plan to get married. You're going to have to rethink your timeline! Things move slowly here, and with getting married in Brazil to a citizen it is no exception. Just because you get married today, doesn't mean that tomorrow you are free to continue living here. You need to have all of your paperwork already put together to begin the PR visa process and submit it literally the day after your ceremony. I think that the moment you arrive here, you need to start gathering the different federal forms you'll need, making the payments for those forms, you'll have to announce in the local newspaper your intent to marry (which has to run for 30 days before you are issued the marriage license - so that eats a month right there!), they don't require a blood test anymore but your future wife MAY need to go to the local cartorio (notary office) and file a paper that says she will be your "guardian" while in Brazil and will support you financially, which will require her to go to the bank and get account information printed out to submit as proof of financial stability since you won't be working. The government doesn't want you to be a drain on the system, as it were. You won't be able to immediately work after getting married. Once you submit your paperwork to the federal police for the PR visa, at the same time you can request a temporary work permit. Once you have that (it can take 30-60 days to receive in the mail), then you can legally work. Most of us expats teach private English under the table or do odd-jobs until we get the permit.
-Americana:
You said you spent about 2 days there. Honestly, that's not enough time to really get to know the place. I haven't been there yet, even though I live close by, but I'm sure it's not that bad. Since you're from Jersey I will assume that bigger city life is more your style (correct me if I'm wrong), so maybe you can look at living in Campinas? Although, if it were me, I'd rather live in a smaller town like Americana and just work in Campinas. You don't have to deal with the crazy traffic and less crime in smaller cities. Also, since you indicate that you're an outdoor type person, there are actually lots of nice places to go for hiking, fishing, etc. Yes, you will need to travel outside of Americana to do this, but it's worth it! I can give you more information on this another time.
That's about the best I can do... hope that helps! Let me know if you need anything else. If you do decide to move here, I'm not too far from Americana and would like to make friends with another American here. I was just contacted recently by an American living in the same city I do. We'll meet up for a beer soon.
Good luck!
Chris
floridaguyinbrazil.com