What is the bumpy stuff?
 

What are the rough areas on the sides of the FD for? They are at the bottom on the sides, and it's just a little strip of roughness?

Sometimes it's an added option. Just tougher as to protect the area from rocks being thrown up by the wheels.

You're talking about the paint protection area. This area, consists of a paint that is more resistant to dirt and rocks. It is found on all FDs.

Is it expensive to repair? My car has a scrape (2x2 inches) there that goes to the metal. It's ugly.