No, they can't.
It´s 18.
Is it legal for a principal and counselor to meet with other than a parent or legal guardian about a student without permission of the parent
Not without parent permission. It could be considered kidnapping without that.
you have to be 14, in order to get it done without parents permission.
No the custodial parent has to have either the courts permission or the non-custodians permission.
18 without parent permission
You have to be 18.
Nowhere.
If you are underage you need your parent's permission.
Without their permission they will have to wait until they are 18. The parents are still responsible for them.
It means that the student can not be allowed without the presence of the parent.
Depends on the ruling during the divorce.