This is completley normal.
"20/20" vision is 20 left 20 right
It is normal for -/+ or +/-
Wrong.
20/20 vision means you see something clearly from 20 feet away that someone with average vision sees from 20 feet away. 20/40 would mean you have to be twice as near an object to see it (poor vision and/or nearsighted). 20/10 would mean you can see it from twice as far away (above average vision and/or farsighted).
Lazy eyes aren't normal. They're common, but not normal.