This won’t be your most helpful answer, but I will say you should ALWAYS, and I mean ALWAYS, apply for FAFSA. Even if you don’t think they will give you anything, it’s always worth applying for because you have nothing to lose by applying (because it’s free) and you might actually get something. It’s worth it. (I don’t know anything about CSS, but it sounds like it’s still worth it).
Also, even after the deadline, you can sometimes still get financial aid from FAFSA, even well past it, so go ahead and apply for it for his first year! Again, nothing to lose!