And when it comes to serious programming then object oriented code will lead to less code in the end. It might look like you type a couple more letters in the beginning, but later, when you have a more complex system it will be a time and a code-saver.

This depends on your system. On a multi-core system like mine I could bake shadows for a complete level with several sci-fi corridors in just minutes. It takes more time when you change your rendering options to max of course. You have to chose quality setup and texture size as well as your second uv-set wisely of course.

Then something is wrong with your model. When I copy 100 files into a project folder, they all appear correctly with materials and textures applied. All textures using bricks01_d as an example get (optionally) merged to a single material. This is extremely helpful and optimizes rendering in the end. I only drag normal maps to each material, change spec values and a new Unity package is done.