Damage to car

Hi guys. I have a couple of questions I'm hoping you can help me with. I was involved in a recent accident where someone slammed into my driver's side rear wheel, causing damage to the front of the rim and the panels to the right and left as well as above the wheel, with minor secondary damage to the front bottom right panel when I hit a curb after the collision. I'm in the process of getting the work assessed by body shops and learned that there is a "skin" that can be replaced, though I've also been told by a more perceptive body shop person that there may be further damage behind the wheel in mechanical parts that won't show up until after I've been driving for a while.

How likely is it that there is further damage if everything sounds and feels fine on the road as well as the highway? Is this just a scare tactic? Also, what else should I be looking for in terms of further damage? Considering the sound and feel of the impact I was surprised more damage wasn't done. Is the Prius particularly durable?

Another, less important issue is that I've had a slight whistling in my steering wheel. Could the car be in need of fluid? It's a 2012, so I wouldn't think it would be needed so soon.

Thanks!