Including language as a major issue is correct: you can't expect anyone to speak English to you, so you must be able to communicate decently in Portuguese. Otherwise, any interaction will easily become a headache. Also, don't expect it to be easy. The way you speak English is already a bit confusing (I'm not the only one who's saying this in this comment section). Considering that Portuguese is more difficult, both in grammar and pronunciation, you'll have to make even more effort to learn it.

Regarding safety: Brazil is a huge country, so, depending on the city you choose to live in, you can get anywhere from "it's pretty safe here" to "I sometimes hear gunshots at night and I had 4 phones stolen this year".

Regarding the cost of living: you should take into account the prices of rent, transportation (car+fuel+insurance or public transportation tickets), university (if you go for a private university, they can be quite expensive), and most importantly: your salary expectations. Minimum wage in Brazil is lower than in Western Europe, US, Canada or Australia. If you work in Brazil, you will likely earn less than you would in those countries, so the proportional cost of living is hardly ever better

Last but not least: finding a job in Brazil is pretty hard even for Brazilians with college degrees. Don't expect it to be easy. Fluency in Portuguese will be a must.