Which of these statements are incorrect, and what are they supposed to be?I'm finding the topic "focusing devices" under "Light" rather a struggle,...

Option one, real images formed by convex lenses are always
bigger than the original object, is incorrect. This is true only if the object is kept
at a distance between the focal length and twice the focal
length.

The focal length is defined as distance between the
focus and the point at which the normal drawn from the focus strikes the
lens.

The principle axis is the line normal to the mirror
and passing through the focus.

Myopic and Hyperopic are
used with relation to a problem of the eye when the eye lens is unable to focus light on
the retina. In Myopia the rays of light are focused in front of the retina and in
hyperopic the rays of light are focused behind the retina. They are also called
nearsightedness and farsightedness resp.