I believe the law is until age 18 or high school graduation, whichever comes later.
Yes, up to age 20 to graduate.
The Rosen Website give 3 situations where child support does not end at 18. If these situations are not stated in the divorce agreement, would they apply simply by default? For example, child turns 18 Jan. 2006 - - does not finish H.S. until Jun. 2006.