depends on how the court papers read. who has custody? No, it might be depending upon circumstances considered parental abduction, but if the father knew where the child was, it is unlikely that such a charge could be upheld. If the father has sole or primary custody he could report it as a commission of a crime and seek prosecutory action. Or he could petition the court for a writ of habeas corpus to have the child returned to his custody. Basically the mother could be held in direct contempt of a court order, unless she could show "just cause" as to her actions. Such as substantiated evidence of the child having been subjected to neglect and/or physical or emotional abuse. If the child was taken across state lines the case could become a bit more complicated, but kidnapping would not be a consideration pertaining to any criminal charges.
Not without parent permission. It could be considered kidnapping without that.
taking someone (sometimes by force), illegally or without permission
Yes, because it is unauthorized act of taking away somebody.
No. Both parents permission is necessary.
If you bring the child it would be kidnapping.
If the non- custodial parent takes the child without permission it is considered kidnapping.
During a normal visitation? No.
Not without his fathers and the courts permission.