Re: Structural Damage
Anything can be repaired by someone who knows what they are doing. A good body shop with frame straightening capability should be able to help.
Does it drive straight and even, no pull ? Does it crab at all (have someone follow) ? Are the tires wearing evenly ?
Next issue is where is the damage ? If in the front of the wheel well ahead of the suspension it may just be cosmetic, it all depends on where and what.
If all of that is good I would be more concerned about the rust.
Finally if the car was misrepresented you may have a case but is liable to come back to "caveat y'all". I would send a registered letter to the dealer advising him of what was found and who found it so that you have a record of what happened as soon after purchase as possible.