OMG, what a nightmare you have to live in. I feel pretty safe to say using your porch as a bathroom is not legal. I looked up your apartments briefly and it seems that they are run by a management company called equity residential. For you this means that there is a higher power than the property management and you will get better results.
These boys sound like tyrants. My personal opinion about these kids shooting at squirrels, I think it's just boys being mean. However, in a residential area, it could endanger many people. I know very little about hunting. But there are designated wildlife areas and I think seasons for each type of animal. Check into the gun laws, they probably have the guns illegally. I would strongly advise reporting these boys to the police.
Good luck with this. I do hope you check into a gun for your protection. And the apartment community should help you by putting motion-detection lighting near your home. Good Luck. I sent this to your email after I noticed it on your question. So, I get to bore you twice! Sorry.
Here is the link to Equity Residential. I am sure the will be appreciative hearing from you. http://www.equityresidential.com/
