Re: Terrain and climate impact on figthing on the battle map
Well, I can't say for sure about Lithuania but you're wrong about Norway with missiles and armour. Bows were commonly used. There's even an royal edit from the 13th century (if my memory serves me) mentionning that Hirdsmen must be equipped with bows. Crossbows then like for the rest of Europe became also more and more in use.
Regarding armors, people tend to forget that Norses were very good traders beside their fighting skills. During the 12th century, it was common to have a mail armour. With their relations with Eastern Europe, it was also quite common to get lamellar armours. Later on, Norwegian Nobles had partial and full plate armors (like the rest of Western Europe). It just took more time compare to Denmark for instance.
This being said and to go back on topic, it is true that horses weren't used a lot in Norway due to the terrain's nature. Having horses is 1 point, being able to feed them is another. They relied mostly on naval support and raiding. They also used to make some kind of barriers (with wood and stones) to not be flanked and to oblige the enemy to focuse on their shieldwall formation. Basically, Norses used to fight in line, holding and pushing forward against the enemy formation until it broke (or until their own formation broke). These points aren't correctly represented in game for now.
Regarding fights in the woods, I have no idea how the trees can influence the cavalry and projectiles (if there's any influence). The ITWE team might have that kind of info
Under the patronage of Flinn, proud patron of Jadli, from the Heresy Vault of the Imperial House of Hader