The letters IAAPA can stand for many things whether they are companies or sayings. The most popular company with those initials is The International Association of Amusement Parks and Attractions.

I guess IAAPA (International Association of Amusement Parks and Attractions) and WWA (World Waterpark Association).

The biggest one in the U.S would be the IAAPA trade show. It's held once yearly in different cities.

No, roller coasters are generally safe, assuming that the rider is in good health prior to riding. According to the IAAPA (International Association of Amusement Parks and Attractions), most deaths that occur as the assumed 'result' of roller coaster rides are generally due to a preexisting condition that the rider had. Be sure to heed all safety information posted prior to riding.