I rolled my fenders with a heat gun and a piece of wood and it did not mess up the paint at all. If you take your time you'll be fine. 18x8 may or may not rub depending on how low you are and offset/ tire size.
Just to let you know works are pretty heavy I have the cr kais in 18x7.5. They do look really good though and they are really strong high quality wheels. They just aren't lightweight by any means if that is important to you don't get them.