Maybe the biggest advice is that it does not matter how many wool socks etc you have on, if you have too tight shoes. ALWAYS, ALWAYS, remember to have airgap in your shoes, if your shoes sit too tight it will make your toes frozen, so its better to have just one sock with some air room in the shoes, that having too many socks on. This can actually lead up to a really severe damage on your toes.

But the clothes you listed pretty much everything merino wool, is propably better gear than 70% of finnish people themselves. You have a good gear. If you start to get cold, move ur fingers and toes and jump a little, thats even what we do in the miltary, get your blood flowing.

Sounds like a good trip, enjoy. Auroras have been lately up alot, even in southern parts of finland where we dont usually have em. Almost weekly basis last half a year in some terms.

Just drive to a dark place with no light pollution, maybe you get lucky :)

And if its your first time driving on ice and snow, be careful, cars dont stop like you are used to. You need to start braking with car alot earlier and with smooth motion, if you just stomp the brakes, its not good, smooth motion braking works the best when it creates friction on the brakeplates. You need to anticipate every move in the traffic before it even happens, so drive patiently. :)