k-ordered array problem
Take your example
$$ A = [1,4,2,6,3,7,5,8]. $$
An array is 1-ordered if it is ordered, and the 1-ordered array corresponding to $A$ is $1,2,3,4,5,6,7,8$. Let's write both arrays together:
$$
1,4,2,6,3,7,5,8 \\
1,2,3,4,5,6,7,8
$$
You can see that matching digits are at distance at most 2.

An array is 2-ordered if its even elements are 1-ordered and its odd elements are 1-ordered. This could be helpful in question 1. A similar property is true for 3-ordered arrays. How do these two properties combine? I suggest you try writing out a few 2- and 3-ordered arrays to see what the possibilities are.