I don't know what would qualify as plenty, but it is certainly true that to this day there are native brazilians that are not even aware of Portuguese language. We still occasionally find previously unknown tribes, although it is a rare occurrence.
Sort of true. Brazil is perhaps less xenophobe than Venezuela and Colombia, but far more than Chile and arguably Argentina. It is all but taken over by a mistrust of Europe and particularly the USA.
It has massacred its native residents to a trace, though. So much so that African ancestry is considerably more common here than Native ancestry, and far more so than many other South America countries, such as Bolivia, Ecuador, Colombia and Venezuela. Perhaps more significantly, it is pretty much ruled by eurodescendents despite its racism being far less overt than that of the USA.
Despite all that, Brazilians seem to be among the people who less care about actual blood in the whole world. We are generaly fairly proud of our intermiscigenation, and of one would be hard pressed to say that a random human being "could not" be Brazilian. There are significant colonies of descendants of Germans, Ucranians, Japanese, Italians, Polish, even Dutch. And, of course, a whole lot of Portuguese and African descendants. Even a few Turkish and Lebanese (Muslim Brazilians are generally well-accepted if perhaps a bit insulated).
You wouldn't believe how difficult it is to tell that some of our Japanese descendants are Japanese descendants. I don't think there is anything quite resembling the complexity and rich opportunities of the Nipo-Brazilian culture anywhere else, although Hawaii and Hong Kong may challenge my statement.
However, there is a downside to it. One that few Brazilians give much attention to. We generally have very loose roots and very little caring for each other beyond actual family, and far too little in the way of actual common goals. Brazilians generaly crave wealth for wealth's sake and hardly even bother attempting to find common goals. Such is the fascinating flip side of our lack of a true national or ethnic identity.