Yes.
Yes.
Kim Dotcom is alleged to have committed a crime against US law. The US requested his arrest by NZ authorities with whom they have an extradition treaty. He has now had his extradition hearing and the NZ court is satisfied that, under NZ law, he should be extradited to face those charges.
You do not have to be a citizen of a country to offend its laws. You do not have to be located within its borders.
For example, if you rob a US bank over the internet you are liable to prosecution in the US no matter where you are in the world. Similarly, if you plot a terrorist attack.