just turn the front assist off on the motorway, the wiper probelm is annoying but mostly only when its drizzley rain for me. heavy rain its not that noticeable to be honest, its a easy fix to be honest. just design a better wiper which I do think wont take them that long to sort out. id be more concerned if the front assist didnt kick in, like some mercs ive seen.
the person who rear ends you is at fault, the car pulled in front of you makeing the car brake as there wasnt enough room for the speed you were doing. the car behind should always leave enough room for any situation that arises.