Is it obligatory to perform ghusl from janabah in Ramadan before the dawn adhan, and is the fast of one in a state of janabah valid if he sleeps before performing ghusl after the time for dawn has begun? And are slight drops of blood after the usual menstrual period considered istihada that does not invalidate the fast?

Fasting while in a state of janabah (major ritual impurity) after Fajr is valid, and ghusl (ritual bath) is not obligatory before it, though it is preferable. However, delaying the Fajr prayer until its time has expired is a grave sin that requires repentance. Bloody drops are considered menstruation if they occur within the usual menstrual period (15 days maximum). All days of bleeding that can be considered menstruation must be made up, as the habit may change. If the duration of bleeding and the habit exceeds 15 days, then the woman is considered to have istihadah (non-menstrual vaginal bleeding), and she is only required to make up the days of her usual period if she knows them.