"The girl is very clever."
Translation:Jenta er svært flink.
It is possible to use the word 'smart' too, it should be a possibility so you don't get the answer completely wrong.
I'm not sure if 'smart' would be fine in the English sentence as it has a variety of meanings, but in the Norwegian one it makes perfect sense: "Jenta er svært smart".
No, "ganske" usually translates to 'fairly/pretty/somewhat/rather/etc'.
There are a few exceptions where it can translate to 'completely/absolutely', but those are more or less set phrases, which I suspect even Norwegians misinterpret at times.
The English "quite" has the same dual meaning.