It depends because if something happens to your child while they are gone then if you give your parents/parents in law power of attorney then they will be able to make medical decisions for your child. So the answer is yes if you want the grandparents to have medical control and no if you don't.
Whatever is respectful and is acceptable to the grandparents.
yes if the grandparents put you on child support.
The grandparents, unfortunately, have to bear that burden & will probably have to become the baby's legal guardians & raise the child themselves.
no, the parents of the child have more rights to the child than the grandparents.
Yes.
maybe if they have custody they could get child benefits
If the grandparents are legal guardians and the child is living with them, the both of you as the biological parents have to pay child support to the grandparents.
A valid passport for the child and a visa if the country you are going to requires one. You should also have a written consent to have custody of the child and a Power of Attorney drafted by an attorney so that you can have the child treated in a medical emergency. See also information in the related question.
In most cases, grandparents cannot receive child support for letting a runaway child live with them unless they have legal custody or guardianship of the child. Child support is typically paid to the parent or legal guardian who has custody of the child. Grandparents can seek legal custody or guardianship through the court system to potentially become eligible for child support.
no
yes, as long as the parents agree to allow their child to live with their grandparents its fine as long as the grandparents can support the child.
No, they must file a child in need of care motion with the court.