Before Brown v. Board of Education, public schools could remain segregated based on race as long as the educational opportunities remained equal. Brown v. Board of Education ruled the "separate but equal" idea to be unconstitutional and unequal. This was the beginning of the end of racial segregation in schools. Hope this helped!
They feared being invaded and threatened by NATO because of NATO's exercise of nuclear capability.
Yes, it required the monarchy to call upon parliament and speak to the "House of Commons" on decisions as they held the "power of the purse". The power of the purse is the spending ability of the monarchy.