Ask your propane company about permits as they'll usually handle this aspect of the installation and file all required paperwork. You can also contact the city code compliance office to ensure that all necessary gas permits and requirements are adhered to before the propane tank installation takes place.
Basically, a hernia is a defect in the abdominal wall that allows intestine to poke through. If the hernia becomes incarcerated (the intestine becomes strangled), then a blockage and rupture of the bowel can occur. This is life threateneing. Many people survive, but are permanently disfigured. A perforated bowel can mean months in the hospital, large portions of the bowel being removed, etc.
There is a small chance it might strangulate. A hernia strangulates when too much bowel (intestine) comes through the gap in the muscle or ligament and then it becomes squeezed. This can cut off the blood supply to the portion of intestine in the hernia. This can lead to severe pain and some damage to the part of the intestines in the hernia.