I've never seen a single person change to the point that they're nude in Norway without it being behind some sort of cover or in a locker room.
Nobody gives a shit if you ask about going to church (most people would say, yeah weddings, funerals and perhaps at Christmas), but a lot of people would be uncomfortable talking about their faith with strangers. If someone I never met came up to me and started talking about Jesus, that would not be cool. Keep that shit to yourself.
The last one is correct though. I've worked in the service industry in Norway, and if someone was rude to me, I'd just be rude back. I once had three people coming in to complain about a delivery, two Norwegians and an American. The Norwegians were polite and understood my position, the American seemed to expect me to grovel on behalf of my company, so I ignored him completely and only answered the Norwegians.