5 I would still regard it as being fluent in two languages. It could either be two languages acquired as a child or learned later, but unless the person is able to function as readily in both, then I would not use the term bilingual, so nothing less than a very advanced level. though not necessarily perfect, would qualify. The trend towards using the term at lower levels makes no sense to me.
6 Yes- quite a few. I teach students doing academic courses in English, so many reach that level.
7 The ability to do anything they can do in their own language with minimal assistance from external sources like dictionaries, much the same way as a native speaker can, at a broadly similar pace.
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