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.
In a hiatal hernia (also called hiatus hernia) the stomach bulges up into the chest through that opening. There are two main types of hiatal hernias: sliding and paraesophageal (next to the esophagus). In a sliding hiatal hernia, the stomach and the section of the esophagus that joins the stomach slide up into the chest through the hiatus. This is the more common type of hernia. The paraesophageal hernia is less common, but is more cause for concern.