Yes. That is typically accomplished by disinheriting that child in your Will.
Yes.
Disowning a child is not a legal concept, and there are no rules. Commonly, people refer to a parent writing an adult child out of his/her will as disowning a child. In this case, yes, the parent could write them out and write them back in again as often as they want.
No, they have to be told.
Yes. You just have to write in your will that your adult child gets NOTHING.
no
A parent can get the medical records of an adult child if the adult child gives express permission.
Is this a trick question? If the child is legally an adult (and therefore 'emancipated') then there is no "custodial" parent.
No, the child can not. The other parent could before the child was an adult. The money goes to the parent to use for the child and not directly to the child.
extremely unlikely
No. The custodial parent is/was the obligor, not the child.
No, they are not.
Only if you prove to be an "unfit" or bad parent. The parent that is an adult has not more rights to the child because they are an adult and you are not.
No, the filing period ended at age 18 for the parent, and age 19 for the adult child.