That's a matter of State law, but, in general, 18.
14 in Canada, 15 in USA
15
That is entirely dependent on state law (or country if outside the USA) where the child legally resides. Most states have laws on the books allowing for such but most of them have periods of time when such an action may be initiated.
Yes, however he should file an injunction to have the child returned.
I don't know about USA, but in the UK it's from 14.
That depends on the child's age and the state (or country if outside the USA) where the child legally resides. No one can provide an accurate answer without that information.
Generally, not if the "child" is under the age of 18. In the USA, at age 18 a person is legally considered an adult and thereby is also legally responsible for their actions.
The USA has had child labor since its founding and still does today - both legal and illegal.
At the age of 17 years old, most states in the USA do not require parental consent if the child moves out of the parental home. I tried to help my sister appeal to the courts in Florida when my niece moved out of her home at the age of 17. The courts as well as every attorney we asked said that Oregon and Utah were the only states which would actually get involved in the matter due to the child not yet reaching the age of 18. If the child is a girl and moving in with a man over the age of 18, you may have a case (but it's hard to prove - believe me, we tried it). My niece actually kept all her belongings at a girlfriend's home but basically lives at her21 year old boyfriend/parents home.
That depends on where you live. In the USA, a child may make that decision when they reach the age of majority (18 in most states but can be as high as 21). You would need to supply your state of residence (or country, if outside the USA) for an informed answer and more information.
Bro-Dependent - 2013 was released on: USA: 31 January 2013 (internet)
That depends on state law (or country if outside the USA) where the child legally resides. If the 19 year old is still a dependent under his or her state laws, only the custodial parent may initiate such an action. If the child is an adult as outlined by their state laws, they may initiate such an action. Some states make no provision for supporting children beyond the age of 18 or graduation from high school, whichever comes first, other states mandate extended support and all states allow an initial support order to be modified to include extended support for a dependent child attending college. If no support order was ever in place, all states provide for a means of filing for support until the state's laws statute of limitations have expired for such an action to be initiated. See why it's so important to include your location when asking a legal question?