And then a general level comment from the Enormous Elk team
In a way, I think that exact names and well-formulated definitions on which god / spirit does what, is maybe a later invention. Or, if we take a look at any contemporary major established religion, we see that despite all the centuries of organized scholarship to define the exact dogmas of this or that religion, there still are a lot of internal disputes, different sub-versions constantly being forked from the main-stream interpretation of a religion.
So I feel that it would be safe to assume that this was going on already a 1000 years ago in pagan Finland. Different regions called their spirits using different names. The definitions weren't set it stone, and a lot of villages or individual people could have their own local variations and adaptations.
Then, later on, when some people got this idea that history can be documented by writing it down, we got lists of deities based on what was known at that time by that person doing the writing. It is very likely that the actual folklore was seven or twenty three times richer that what got documented.
Yes, I appreciate the approach of wanting to familiarize with the details, names and natures of the ancient Finnish spirits and deities - or those adaptations we have in the game. Yet, I feel that the one thing we learn also in the game is that gods, deities and spirits are little bit elusive. So, ones own personal imagination is a valid guide as well, when venturing into the realm of seldom-seen aspects of our world.
All that being said, I also have an answer to one of the details asked:
-How can the spirit affect the everyday life of an individual?
I don't know for sure, but I'd guess that one way is to send accidents and other unfortunate events. When an individual feels that something unfortunate and highly unpleasant happens, it is rather tempting to assign that to the spirits, or some malicious witchery by other people. Go fishing, return with empty hands having caught only cold, and lie down in fever? Probably a punishment from the water folks? Or maybe it is Jussa from the neigbouring village - a week ago I instulted Jussa, and now he has sent his unseen spirit minions to harm me, maybe I need to go back to apologize him?