Your ears hurt because water pressure pushes in on your ear drum. In your scuba course, you'll learn a simple technique to equalize your ears to the surrounding pressure, much like you do when you land in an airplane, and they won't hurt at all. In the movies and on TV, divers are always running into sharks or eels. Virtually all aquatic animals are passive or timid. There are a few that can bite or sting defensively, but you can avoid these simply by watching where you put your hands and feet, and by not touching any animal you don't recognize.
Statistics show that recreational scuba diving is about as safe as swimming.
I need vision correction. Not at all. If you wear soft contact lenses, you shouldn't have problems wearing them when you dive. If you wear hard lenses, you'll want the gas permeable type for diving. See your eye doctor about these if you don't have them now.