"The attorney will send the dog owner a demand letter today. "
My gosh, you don't need an attorney to write a demand letter! Googol Small Claims Court filing in your county. Googol "How to File a claim in [county,state] small claims court. And, everyone else - go to your community college or...
1. Photos, evidence, documentation -> Animal control complaint
2. Small claims court; fowl costs; fence repair costs, filing costs
3. 12 ga shotgun buckshot or slug load(s) Three should do.
4. In my state you would be responsible for disposing of the dog's carcass - check local statutes!