Also, while Norway would be good experience and you might learn Norwegian, it’s not much use outside of Norway and can’t really help in the EU either (as Norway is not in the EU).
1. Just because Norway isn't part of the EU doesn't make Norway a passive member of Europe. It's far, far more active in European affairs than other countries which are part of the EU.
2. Norwegian is very similar to Danish and Swedish, and both Denmark and Sweden are part of the EU, although like it said it doesn't really matter. I guess this is about 20 million speakers, then, but most of them speak English. That being said, Scandinavians are pretty awesome people, and I think learning a Scandinavian language is good. But I'm biased of course.
3. Like I said, 'usefulness' shouldn't really be a criterion for learning a language. Going to Scandinavia for exchange is a good idea, and is popular amongst westerners for obvious reasons. Learning the local language is fantastic and adds a lot of credibility of you want to work in foreign affairs.
Put it this way, Arabic has around ten times the amount of speakers than Danish-Swedish-Norwegian. So, you might say to yourself 'I should learn Arabic as it's more useful'. The problem is that not only do lots of non-Arabic speakers think that and learn the language, but remember that since the percentage of truly competent English speakers is (essentially) the same across all non-English-speaking cultures, the amount of competent speakers in the culture also increases.
So you're really competing against a larger pool of people for a proportionately larger pool of jobs. = There's no point taking that approach to learning a language, unless you can learn one quickly and proficiently enough to suit a random job advertisement you see.
To become 'fluent' for business/academic purposes in a language like German, you really need to learn the language consistently for a good 3-5 years, with at least a large block (ie a semester or year) of which are in that environment communicating solely in that language. If you don't reach this level, places like the DFAT, ASIO/ASIS, AFP, hotels, etc, simply won't want you translating and interpreting. What anyone else says is effectively wrong, I'm afraid, and generally stems from people who have no real experience with languages, have started learning a language and think that language learning doesn't plateau (false), or people who are misinformed by film and TV representations of spies who can speak like 20 languages by reading a book and taking a short intensive course.