As stu has said get it to H Dev. It's a common problem for the banana arm bushes to fail , they can be replaced without replacing the whole arm providing the ball joint at the other end of the arm is ok. That won't be the reason the rear is creaking though. Oh and please don't just replace one rear tyre , replace in pairs. Why on earth Nissan would suggest that is beyond me and if your on a budget get a good mid range brand, definitely not event. They've also quoted you for 225/45/18 which is the front tyre size,providing your running standard wheels.