Normally, in mainland Norway (Svalbard is different) you would not be expected to change shoes at the door of a normal office. It would be at your discretion; wear what makes you comfortable.
In a private home however, at least in an informal setting, you would very often take off your outdoor shoes and either walk in your socks or wear clean indoor shoes.
Can a restaurant manager call the police if I chose not to tip?
No, once you have paid your bill you have fulfilled your legal requirement to the restaurant
including any 'gratuity' entry the bill may contain
Whether it is a good idea not to tip is another question.
You will find very many questions here on this topic that is specific to the United ...
I'm not sure whether the rules differ in Hungary, but it's probably the same as in Germany and Switzerland:
If you're sweaty, you should always shower before entering the plunge pool. (You don't have to observe this if the "plunge pool" is a natural body of water such as a lake.)
Any number of people can use the plunge pool at once, if they fit comfortably....
I worked for a couple of months in an office at the site of the former Oslo airport, starting in a snowy foggy early March. I don't remember seeing any evidence that anyone was changing their shoes. I certainly wasn't.
Nothing, you can keep it as a memento.
Last year I travelled to Singapore with my friends, our return flights were different and I was the one who checked out last from the hotel. When the receptionist asked me about the other 2 cards, I told her that we lost them somewhere. She said no problem and wished me a happy journey.