The Inheritance

What explains the inheritance issue in pride and prejudice?
Why should the Bennetts, upon the death of the elder Bennett, bequeath the estate to his brother's son, but not to his wife or daughter?What is the purchasing power of the 10,000 pounds a year mentioned in the passage?Why did Elizabeth's mother begin to insist that she marry, just to keep her inheritance?Why did the marriage fall apart when Elizabeth refused? If Elizabeth was allowed to marry, why not Lilliard?And why did old Bennet, who seemed calm and wise but cared little for worldly affairs, marry such a vain and vain wife?