Exposing one's Satr

Q: I have heard that a person who reveals his satr to another person, his salah will not be accepted for 40 years. Is it true?

Q:

1. What is the Islamic ruling, fardh, wajib, sunnah, etc. of covering the women's hair while at home with one's family?
2. What is the reference of the story of Zulaikah the wife of Haroon Ar-Rasheed who used to cover her hair when Azaan is given?

Q: My wife is overweight so she conceals her body from me. We do not stay with my or her parents. Is she allowed to make purdah from me? I am the husband.

Q: I am 52 years old. I wear a hijab but not a nikab. An Alima advised me that this is fine as long as my neck & chest is covered. Please advise if this is true or am committing a sin by not wearing a nikab?