Not in and of itself, however is the parent has a disability that prevents them from being able to care for the child, than it becomes an issue of safety.
Unless there are unusually circumstances, once a minor becomes an adult under the laws of the state in which he or she lives (or as stated in the support order) child support ends. If he or she has established residence outside the custodial parent's home with the approval of the custodial parent, the obligated parent should petition the court to have the support order amended or rescinded. Child support money is for the support of minor children and not "owed" to the custodial parent. The custodial parent does have the legal right to sue the obligated parent for any arrearages or "extra" expenses incurred while the minor child was in his or her care.
Interpretive as any obligation to support runs until age 21
Not ordinarily, because the child becomes an adult at 18 and can make whatever decisions he or she wishes. There are some cases (notably legal incompetency) where the child does not gain free status as an adult, and would continue under the supervision of a parent or guardian.
Legally, if the child is still a minor than no. If the child is underage and leaves the home the parent could be charged with abandonment. It is the parents reponsibility to look after the child until they reach adulthood. What the child wants does not really matter.
yes you could
Yes he/she is now an adult.
The parent. In most states, the parent is responsible for the child until the child officialy becomes an adult.
That parent would be in violation of a court order, so yes, they would be in trouble. The adult makes the decisions, not the child. The child should be put into a car and driven home.
I don't know about 'perceived' but they do have an objective role. To morally guide the child and prepare him for independence as an adult.
Not in and of itself, however is the parent has a disability that prevents them from being able to care for the child, than it becomes an issue of safety.
18 unless they go to court and have it ordered differently
Potentially. If the proper authorities find reason to believe that the child is at risk of obtaining drugs illegally, or that the child is also at risk of an overdose, the authorities can remove the child from the home for "Child Neglect".
They can tell them to leave. Once a child is an adult, usually age 18 depending on the state, the parents are no longer legally responsible for them. They can even charge them with trespassing if they don't leave.
Not on taxes no. The parent the child lives with has the main right to claim the child. But if that parent can't or doesn't want to then the other parent can
The right to tell them to move out. They are no longer responsible for the adult and can have them forcibly removed.
Receiving mail as a guest in your parents' home does not give you any legal rights in their property. You may be entitled to notice under state laws if they want to evict you but you have no other rights in the property.