The four programs he must choose from are humanities, international studies, middle school IB (focus on study skills), and performing arts. I am leaning towards either the IB program or the humanities program. I'm concerned that the rigor of the IB program might be too stressful, and that the humanities program might not prepare him for the structure needed in high school.
I think the humanities curriculum would be helpful for him. You might want to also get him some tutoring help in algebra. He might never be a straight-A math student, but he may be able to work through his math difficulties, really grasp the material, and get Bs. That would be very positive.
Remember that the most important thing you can give your son is to support him through any of these courses. His academic education is only part of the success equation. He also needs to develop his ability to be with others and develop his own sense of what his true passions and interests are. With a mother as interested as you, he is very fortunate.
My book, Majoring in High School , might be good for him to read this summer. It's all about how eighth-graders and freshmen can prepare for high school so that they can make the most out of the opportunity.