It is recommended for a Muslim to do wudu before ghusl following the example of the Prophet (peace and blessings be upon him). If the shower is done to cool down or to clean oneself, then it does not count as wudu (if wudu is not done before or after it).

A woman does not have to undo her hair when she does Ghusl following Janabah (impurity following sexual discharge), but she must make sure that the water reaches all parts of her body, including the hair and its roots.