Have you been able to do any research on ferrocement?
I found a slightly different way of doing ceilings and roofs that you might be interested in. It is called timbrel vaults or Catalan vaults.
Basically, it consists of creating a vault using tiles, and it requires very little formwork. The tiles then become the form for the roof, so you place your insulation on top of the tile vault, then a ferro-cement cap that could be sprayed on or applied by hand. It removes the need to stucco from below, which is a major pain with ferro-cement ceilings. Also, it reduces the need for steel in the ceiling, which saves a lot on building cost and complexity.
You guys could make a tile machine similar to the Liberator CEB press, and use the tiles for the ceiling and the floor, making a building almost completely out of CEB-type material.
We are trying this method out on a small building in the next few weeks, and I will let you know how it goes. The method appears to be very promising, and it would make ferro-cement roofs very easy and fast to do.
Good luck, Abe"
LifeTrac is their impressive DIY tractor, picture above. (And at the very bottom of that page, a well placed link to Low-tech Magazine).