Putting too much law into personal lives will create problems.In islam a man CAN Marry up to four women if can treat all of them equally not SHOULD marry four because a man is a man. Who will decide if one can treat all four equally? Logically the wives should have a say. It means all wives would have to be aware of each other and should even know exactly what the other three are getting (money, attention, etc) . There lies the role of courts.
No, bcz God gave us the permission. There is no need to create rules on top of permissions God gave us.Is the consent of first wife necessary or not?