Are the brown or yellow fluids that appear after dryness, or light spots of blood on the fifth day, or on the sixth and seventh days, considered istihadah (non-menstrual vaginal bleeding) requiring wudu for each prayer, or are they part of menstruation necessitating ghusl? And does performing ghusl during the early days of menstruation affect its duration, such that the fourth day, when a significant amount of brown fluid appears, becomes a day of hayd (menstruation) or istihadah?