I can't speak to all of the things you want to learn, but I've learned some of them on my own. For calculus and linear algebra I'd go with Khan Academy, especially since it seems like all you need is a refresher for calculus. Graph theory and discrete math I did with MIT EdX courses. Their discrete course is pretty nice and I found it very easy to follow along with.
Constraint solving and optimization problems aren't things I self studied, but you can find a variety of resources to help with those based on how you learn best. For me, I did them by taking a class and relying heavily on my textbooks.
+1 to Khan Academy. Explanations are super clear. Their website allows you to work through practice problems too, which I think is the most important thing.
Constraint solving and optimization problems aren't things I self studied, but you can find a variety of resources to help with those based on how you learn best. For me, I did them by taking a class and relying heavily on my textbooks.