Quote Originally Posted by Blacky View Post
So, does anyone have an idea on how to proceed or which tools to use to be able to keep walls straight, angular connections neat, and maybe be able to divide evenly or smartly space (to put column where they should be, and aligned)?
Yes. Stop using raster editors like Photoshop for this sort of task. From your description, you want to treat the walls sort of like objects that you can resize, move around, connect and so on. Trying to do this just by flipping pixels on a grid is madness. Use a tool that works the way you are thinking: a vector editor.

Illustrator is the 800-pound gorilla of vector editors. There are others. I like VectorDesigner, for example.