1.
https://www.google.co.uk/#q=youtube+NZ+accent Give it a listen, and see what you think! (Warning, some of the people who recorded the clips about NZ are joking. We had someone on the forum a few years ago who believed the girl who said all males who reach the age of 21 get given sheep - !)
2. It depends on your nature, and how hard you work at it - impossible to predict.
3. Many Brazilians have come to NZ. You need to submit your qualifications for an IQA
http://www.nzqa.govt.nz/qualificatio...ns-assessment/. NZQA is a government body which is tasked with investigating any foreign qualification, after which they state what NZ Level it is at, and any NZ qualification it is comparable to.
I suggest you look at the INZ website
https://www.immigration.govt.nz/new-zealand-visas, to get an idea of the different sorts of visas, and the requirements for them. There is a lot of information on INZ. It's the best way of getting to know where to start.