What is the ruling of Islamic Law on the colored discharges that appear one or two days before the menstrual cycle?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
Colored discharges carry the same Islamic ruling as blood, whether they appear at the beginning or the end of the menstrual period. This remains true even if the discharge is intermittent—appearing for some days and stopping for others before returning—provided that the total duration does not exceed fifteen days nor fall short of a day and a night (24 hours). This is because the minimum duration of menstruation (Hayd) is one day and a night, while its maximum duration is fifteen days. Furthermore, the minimum period of purity (Tuhr) between two menstrual cycles is fifteen days, and there is no maximum limit for it. And Allah the Exalted knows best."
Can I start fasting based on the moon sighting of another country?
You must follow the moon sighting of the country you are in.
What is the ruling on performing ablution (wudu') and ritual bathing (ghusl) with Zamzam water?
It is permissible to perform ablution and ritual bathing with Zamzam water. However, scholars disliked using it for cleaning after relieving oneself (istinja'). And Allah the Almighty knows best.
Is bleeding that lasts for nine or ten days considered menstruation (Hayd)?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
If the duration of the bleeding does not exceed fifteen days, then all of it is considered menstruation (Hayd), even if the regular cycle ('Adah) has changed. And Allah the Exalted knows best.