Yes, it is fixed at 3 days. It does not vary under any circumstances. The 4th day is the day to take bath and from the 5th day on wards religious activities etc. can be resumed. This is what is mentioned in the Smriti scriptures.
If discharge continues to happen even after the period (of 3 days) is over, then that does not create any impurity.
This will be ...
Beating generally doesn't means to beat physically or harshly. These type of verses are present not only for women but in many cases. This is only for the purification of soul and we should not beat harshly as written in Shiva Purana.
48-49. After sprinkling and striking lightly the disciple and remembering the Ātman of the disciple in his own, the ...
Here's what the Motilal Banarsidass translation reads for the same:
CHAPTER TWO HUNDRED AND TWENTYSEVEN
The code of criminal laws
41-42. A king should kill those who cause the death of cattle by magic
spells. One should not converse with another's wife and should never
copulate with a forbidden (woman). A girl choosing her husband herself