Don't be scared - it's nothing to worry about!
The puff of air is to check for glaucoma, and many doctors use a different method now. This is important to me because the anticipation of that air coming at my eye is torture lol (it's actually not terrible, you just have to put your big girl panties on for a moment and deal with it)
Other than that, it's fine. The reason they ask 1 or 2? 1or 2? is they are trying to fine tune your Rx by using a series of curved lenses at different angles to give you the best possible vision correction. Your basic Rx is given to them in the beginning of the exam/tests by a machine called the refractor, which detects how the light bends as it moved through your cornea and lens of your eye. This gives the doctor a starting point, but since everyone's eyes are different, they use the manual lenses to do the 1 or 2? exam to give you the best possible lens curves in your glasses.
I worked as an optical lab manager/optician for many years. If you are interested in knowing what those numbers on your rx mean:
Sphere (the first number) - the curve of the lens of your eye. A +value (+1.25) means farsighted (reading glasses), -value (-1.25) means nearsighted (distance glasses). The higher the value in either direction=stronger Rx
Cylinder (the 2nd #) - indicates the amount of lens power for astigmatism, if you have it.
Axis - the degree the lens is turned to accommodate astigmatism
OD= right eye
OS= left eye
OU= both eyes