Hi - and welcome to Norway
1. Read the posting I made in one of the other threads in this forum:
Holiday in Norway with a german Model S and Family
The contents of that post is not specific for Germans only
When it comes to the various charging schemes you will find that most schuko plugs are free - some require the municipailty parking key to open the box where the plug is located. Most of the boxes are to small to fit the older Tesla UMC Schuko plug. The newer model (nicknamed pigtail) fits fine. Alternatively bring a short extension cord - make sure it is 2.5mm2 or more as you will send 13A through it.
Many 22kw are also free. Some require a SMS msg sendt to the number listed on the outlet to open the lid, then plug in, close the lid and electrons start flowing, send another SMS from the same telephone to stop and unlock again.
The commercial charging companies (those that demand payment and a form of card) have not yet - to my knowledge - started to offer roaming. One membership per company seems to be required. The major ones are Fortum, Grønn kontakt and Ishavsveien. I think you would be able to do without these.
Use the info on
Hurtigladekartet to find more info. All chargers from all companies are listed - with info on payment etc... Some Statoil gas stations have chargers now - more are coming - and they usually let you pay inside and then activate the chargers (22kw AC type 2). Hurtigladekartet is in Norwegian. You should be able to make sense of it with your Dutch background - alternatively use Google translate.
Good luck!