The "adult child" can apply for a restriction order if the threat is serious.
(The term "adult child" is contradictory, a more accurate term should be used.)
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.
Custodial, as he/she has primary control and influence.
extremely unlikely
No. The custodial parent is/was the obligor, not the child.
When a child rapes the parent the child is charged according to the laws of that state.
Nothing extraordinary happens. You are just a child of a parent.
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.
Only if the parent is the legal guardian of the child's person. If the child is a danger to herself or others, the parent can petition the courts for involuntary commitment.