A question will generally have the verb first. A statement will have the verb second. Question: Har jenta en edderkopp? Statement: Jenta har en edderkopp. It can be the same in English. Question: Has the girl a spider? Statement: The girl has a spider. Of course in English it is more common to phrase the question as: Does the girl have a spider? But the other way is grammatical too.
True. And just as with close-sounding words in English, you sometimes need to rely on context and/or grammar to know what is right. Here, it would be ungrammatical to use "jente" because that would be "Does girl have a spider?". Just as you must say "Does the girl have a spider?" in English, you need to use "jenta" (the girl) in Norwegian.
that's not truly proper english. that's a statement with a question mark. This isn't italian ;) we need to change the verb-subject order in english. http://www.englisch-hilfen.de/en/grammar/frage.htm
this link is for german speakers learning english, it should help