Joaco,
I would pull the walls up without the door breaks and add boxes where the doors are and boolean them out after. It's much easier than adding in the header.
I build my curve lines with the rectangle where I can and then either trim them or boolean them or separate them to build the curve walls. that way I can guarantee they are straight. Many times I think the walls are straight and they will be out by some small amount making it difficult to make a nice looking wall. If I'm in doubt about straightness of curves I use the align tool with the points.

Val