building house aprox 150000 pounds using 6x6 posts--what is recomended spacing from 3ft high to 12 ft high
You need an engineer to know definitively what your requirements are for your location and design. I am assuming you did not consult an engineer since they would have the spacing specified in the plans. ( it is unlikely they would they have specified 4 feet deep )

We can not answer your question because we do not know the required info nor would it be wise for you to take advise from the internet instead of hiring a professional engineer. 

A friend of mine bought a house in foreclosure on the hillside of Anchorage many years ago.  It was built on 6"x6" timber piers some of which were only 4 to 5 feet deep as you plan to do. The house was listing badly at one corner as the piers at that end of the house had not been of sufficient depth.  He had to pay to have the house jack up and moved to a proper foundation we built. He then built another structure nearly on the same site as the older one. We hired a pile driver to drive 8" well casing pipe down to bedrock with steel I beams on top. It is not listing or sinking.