Here are some edited highlights of email I have replied to. They are more in the order I receive them than in any logical sequence. One day I'll sort it out. If you have any questions that are not covered here please feel free to ask. Actual values are given in the table below.
Good insulation results from the greater thickness of the wall.
Further, I should imagine that a higher percentage of cement would be advisable and some sort of waterproofing agent be included in the mix. My suggestion regarding crew is to get one experienced person to act as a foreman under your command. He can train the rest pretty quickly. Another good idea is to offer a day's free work to someone building somewhere so you can experience what it is like. Doing that was a real eye-opener for me.