Are story and history the same in norwegian (Historie)?
Yes, but you can also use "fortelling" for "story", if you're worried about the ambiguity.
Whats the difference between lang and lenge?
"Lang" is an adjective, and can deal both with physical and temporal length.
"Lenge" is an adverb, and always has to do with time.
Takk for lang forklaringen. Lenge tid siden!! :D
Is eventyr interchangeable with historie?
They're not interchangeable:
'eventyr' = 'adventure', 'fairytale'
'historie' = 'history'