How to determine live/dead load?

[JB Griffin]

How does one go about it?  I ain't no carpenter. I just saw lumber for a living. 

I am going to build a 2story pole shop with living quarters above. 20x24 main building with 20ft side sheds to be added later. I am planning to use 12ft erc 6x6 planted 2ft in the ground( frost line is 12-16in here) spaced 8ft apart along the sides with free span along the 20ft ends.  

On top of that double banded (inside and out) with 2x12syp set into notched top of posts and 2x10 or 12syp floor joists across that (actual span of 19ft) and stud frame on top of that with 5/12 pitch metal roof.

Will this work?