Doing college (minor dependent son) outside US under GC pending status, allowed?

[pankajb]

My son is planning to do college outside US (Europe or Canada). We have our I485 filed and GC is pending. I have EAD and my son has Advance Parole. Is he allowed to do college (under grad) outside US while GC is pending ? If he does so, will there be any issues/impact for him for his current GC process? Can he enter US periodically (e.g during college vacation breaks i.e .once in 6 months or so) based on the Advance Parole ? Please advise.