Not very much. I am quite unclear what the parameters of such an issur would be. The gemara in BB talks about it in terms of using their din of chazaka on land.
Ok, it is not nice. Is it a property right? Does the city even consider it a property right?
3. Again, back to Halacha, knowing that the police officer who tickets your illegally parked vehicle is likely going to be a gentile, how do you reconcile committing Chilul Hashem by openly breaking the law especially if you have left seforim or other Jewish articles visible in your vehicle?
I do not think parking illegally is a chillul hashem.
I am not aware of the hezek you would be charged with. I suppose if you hit his car, you should leave your name and number so you could go to a din torah.