National Match sights usually aren't graduated in 100-yard increments.  Match shooters keep track by how many clicks up or down they need to go for each stage or position.  As far as the clicks, that depends on the sight.  They usually have either 1/2 or 1/4 minute clicks.  

Depends on who's NM sight you've bought and which version.  It could be 1 moa per click or 0.5moa per click.

Easiest (most fun) way to check is to go to the range and fire a 5 shot group at 25 yards.

Go up 16 clicks.

Shoot another group. then measure the distance between the center of the two groups.

a 1 MOA per click rear sight will have moved the group 4", a half MOA group would have moved the group only 2".

This of course assumes you shoot tight groups for the best precision.  

Sight adjustment (moa per click) will be ( measured distance * 4 ) / 16