Does everyone have scoliosis even if its just minor?

No. There are two major types - developmental & degenerative. The first occurs in about 1.5% of adolescents, but only a small fraction is serious. We measure severity by degrees of curvature. More than 10° is significant, but treatment is reserved for greater degrees of curve, usually more than 18°. Your doctor (not chiropractor) is the best judge of this problem. The 2nd type is in older people.
Spinal asymetry. Scoliosis is a lateral curve of spine bigger than 11degrees spinal asymetry is ubiquitos under 11 with no rotation is not true scoliosis people with back pain and spasm often have a small curve, spinal asyemetry this is not scoliosis it resolve when the pain resolves scoilosis is a painless condition below 30 degrees.
No. As a pediatrician, scoliosis occurs'but is relatively uncommon.
No. Most people are straight when viewed from the front (with an x-ray); there are normal curves when seen from the side. With scoliosis, there appears to be curves on both; in reality there is abnormal rotation in the bones, best seen on sophisticated imaging (ct, mri), though it is present on plain x-rays. Mild scoliosis may not be apparent to the eye. More pronounced curves can be seen others.