How much of the Earth's surface area is ocean?
71%.  But the area of continents isn't 29%. 

How deep are the oceans?
The deepest measured point is 11,020 meters, in the Marianas trench.  The oceans' average depth is about 3800 meters.  Here's a follow-up question for you: How would you determine these 2 numbers on your own?

What is the minimum structural, metabolic, and genetic equipment of a postprotobiont that one would consider to be a true primitive cell?
Your question relates to the origin of life, a topic that has received a lot of attention in the scientific literature, especially since the discovery of deep sea hydrothermal vents in 1977.<br> I think you might enjoy beginning with an article in Scientific American.  There are further references therein.  Here is the reference: <br> Title:  Life's Rocky Start<br> Author: Robert M. Hazen<br> Date:   April 2001 <br> Pages:  76-86<br> Abstract: Air, water and rock were the only raw materials available on the early earth. The first living entitities must been fabricated from these primitive resources. New experiments suggest that minerals - the basic components of the rocks - could have played starring roles in that dramatic feat.