When it comes to the guest list, it is really a headache to try to limit the guests to 4-500, here everyone is expected to be invited. Weddings and deaths, then you expect to meet the whole family. It is also not common to invite someone only for coffee and cakes, but it is okay to invite only for the wedding day and not the rest of the 3-4 celebrations. With time constraints and many activities, only 1-2 guests from each household go if it is not the closest family and good friends.
When you invite someone, it is best for the parents to deliver the card personally and not something you just send in the mail. It is only accepted if it is far away, other cities and abroad. The Finstasen is supposed to be on when the invitation is delivered and in fact neither the bride nor the groom is involved in it! The guest lists have become smaller over time than when my parents got married, but from Norwegian perspectives, these are still very large weddings. The norm is around 4-500 guests.