It depends on the person, actually. Some people have menstruation for a week, some only 3 days. Hope this helps ((:

Not really

Yes - during the average 28 day cycle 3 days after menstruation would be during your fertile phase, thus pregnancy risk is very high.

Endometrium, blood, and the ovum

When the uterine lining sheds this is typically called menstruation. Although women on hormonal birth control will experience a faux period in the form of a withdrawal bleed.