By the way, Viking is a historian term, as far as I know. It was not used in the period or at least not as it is used now. Correct me if I'm wrong.

Also, surely you wouldn't call (now or then) Mediterranean-born pirates Vikings.

I've seen archaelogical artefacts from East Baltic graves with runes. The commentary in the exhibition stated that runes and rune-related shamanic practices were imported across the Baltic sea. I'm not a historian, I'm only conveying what I've been told by enthusiasts or casually ran into.

I wouldn't be surprised if Stockholm started out as an attempt to protect the cities around Lake Mälaren from raids. It is not known why the city is called Stockholm but one theory is that ot comes from logs driven into the lake to control who goes in and out of the lake.

That's a somewhat sad question, because we hardly know. Not enough written record exists and "paganism" was increasingly outlawed during the past millenia to the point where we're out of people that had it handed down to them. The missionaries doing most of the recording were also the ones actively suppressing its survival. I'm aware of at least one revival movement that was active during the last 50 years, but the main instigator seems to have died without leaving a meaningful succession, and thus the preservation may very well have failed. Unless someone invents a time-machine a la Assassin Creed.

The etymology of the word 'pagan' originally meant hillbillies / dumb country people. It was a slur because the towns and cities adopted Christianity before the country people did. So, 'pagan' typically means the pre-Christian religions of Europe.

In the context of European Antiquity and Middle Ages - this means the original polytheist religions of the Romans, the Greeks, the Slavs, the Celts, the Germanic people...

Yes, from the context of Abrahamic religion and the cultures descended from it, all religions and cultures which are not Abrahamic are by definition pagan.

by definition, yes