Native speakers absolutely cannot infer the pronunciation of an unknown character. If they haven't specifically studied and learned that character before, even native speakers can not guess at the pronunciation, although they may be able to guess at meaning.
]]>With regard to learning English (or any language for that matter), the good news is that you don't need to spend very much time consciously studying vern tenses and grammar, and in fact, doing so is often the reason people can never learn a language well. They spend almost all their time learning information ABOUT the language (i.e. building their declarative memory) and not enough time actually listening to and speaking the language (i.e. building their procedural memory).
]]>Also, while English is largely derived from Latin and Greek, many other languages are built from themselves. A giant German word is made up of 4 tiny German words. A giant Japanese word is made up of 4 joyo kanji.
I would expect, based on what little of these languages I know, for English to be at or near the difficulty limit. If you're learning anything else, it will probably be easier than these numbers indicate!
]]>Anyway. I think that for a native speaker of Chinese 3000 learned characters is enough to read the newspaper, because they can infer the meaning and pronunciation of unknown characters.
For us non-native speakers 3000 might not be enough, even though it is possible to guess the probable pronunciation after learning 3000 characters.