There is a unanimous agreement among Muslim scholars that washing the hair is obligatory for both men and women when performing ghusl. However, the woman who has braids is not obliged to unbraid them when performing ghusl after intercourse. Rather, she can pour water over them till water reaches the roots of the hair and the scalp.
Sheikh Ahmad Kutty, an Islamic scholar, while responding on this said:

You need to wash your hair with water but you need not to undo the plaited hair; it is sufficient for you to pour water over your head.
It is a common knowledge that following sexual intercourse, both men and women are obligated to perform a complete ghusl (ritual bath) in order to be eligible for worship. A complete ghusl involves washing the entire body including one’s hair.

As for washing clothes after the menstrual period, you should know that the blood discharged during menstruation is impure, and so if  your clothes have traces of such blood, you have to clean them if you are going to wear them while praying.