Not box 2, use the amount the college was paid (which may not be the same as box 2).
Yes, he will still be a dependent on your tax return.
Yes, the difference would go on your son's tax return. If his total income (including the taxable scholarships) is less than $6350 in 2017, he won't need to file a tax return.
Correct, that difference will not be on your tax return, it would only be on his tax return.
However, pay special attention to what Hal_Al mentioned above. In most cases, you can CHOOSE to make up to $4000 MORE of his tuition taxable, which would go on your son's tax return. Although your son would owe some taxes on that, you would receive up to $2500 CREDIT on your tax return (assuming you qualify for the American Opportunity Credit).
