Origin of Life

Is it true that the Precambrian atmosphere lacked oxygen, and thus would have allowed prebiological synthesis of organic molecules?
Are experiments such as those of Miller-Urey and Sidney Fox good examples of abiogenic synthesis of life?
If organisms evolved in an environment lacking oxygen on the primitive earth, wouldn't they be different from those we have today?
Could photosynthesis have evolved early and provided the oxygen needed for the respiratory enzymes
What would be necessary to have a living cell, as a minimum?
What is the current state of studies on the spontaneous origin of life?
Ó 2010 Arthur V. Chadwick, Ph.D.