How does the national guard ROTC SMP work as far as paying for college?

Yes with SMP, no with GRFD. Basically, if you do SMP, you'll go to basic and AIT over the summer, come back to school and continue your education. The Guard will pay for your schooling on top of your pay as a private (or whatever) and some sweet bonuses they doll out (housing/board). During the rest of your time in the Training Corps, you'll go to drill for one weekend a month just like any other guardsman. When you commission, you leave your unit, your Guard contract becomes void, you are igned to a new unit, and sign a whole new contract with Active Army.