You can place the visible lights wherever you want them, say for example the top half, and then use the buydebug lighting in the bottom half - if you have lighting in both parts the sims shouldn't get a 'dark' moodlet.
For the walls and windows, you can place a section of wall (at least 2 tiles away from the area) and use that as a guide to level the section of lowered wall only above the door/window (with CFE turned on). Your lower wall will look like this:
____
/ \
__/ \__
So you will need to use a wall covering that is monotone, as the diagonal parts are stretched out. Bricks and panelling will look funny, but with plain paint with no trim it is barely visible.