Has he filled out the paperwork for alternate entry? If not, that is one of the first things that he needs to do. He also needs to send his SAT score to NMSC.
With respect to cutoffs, the only cutoff that has been released is the commended student cutoff (207). The semifinalist cutoffs will begin to trickle out in either late August or early September, but many/most of them will not be known with certainty until NMSC notifies the schools in early-to-mid September. While previous years can give you an idea about what the cutoff will be for your state, no one knows until NMSFs are notified of their status in September.
Since he has already taken the SAT to enter via AE, he will not need a confirming score if he is a NMSF. Also, tuition discounts are usually for finalists who designate that particular school as a first choice, but there are some schools that have very attractive packages for NMSFs (Tulsa for instance). Good luck!