At the time that you separate, both parents have custody of the children until a court makes an order or both parents enter into an agreement. If you cannot agree with your partner about custody, it is important to retain a lawyer as soon as possible.
The court considers what is in "the best interests of the child". This may include who was the person who did most of the parenting of the child and the court may take into account the child's wishes.
This is when one person has full decision making responsibility for the child and usually the child lives with that person.
Joint custody means that both parents have the same rights with respect to the children that they had when they separated. Joint custody works well if both of you can co-operate about parenting your child. The child can live with one parent; or with both parents for equal or differing amounts of time as the parents agree.
Only if the other parent is in agreement. Otherwise, a court will have to decide whether or not you are able to move away. Recent cases show that a court will look at what is in "the best interests of the child'.