We will start by removing the window and door in the picture. How should we proceed? We have supports and have planned to inset a similar beam as the existing one, i.e., 45x220x360. But where do we begin? How much of the wall on each side of the opening do we need to remove to get access? Are these two beams sufficient since it seems like the entire structure itself carries currently? The beam that's there now is nailed into the standing studs from the outside. The beam also has a notch on each stud that it can rest on, which it currently doesn't because there's a tiny gap between them. So, the fact that it's nailed into what we will remove must also be considered for the load-bearing capacity of the new construction. A step-by-step description would be appreciated.
Is this an old exterior wall? What is above? I would like to see a section through the house to be able to determine how you should proceed.