Sounds like the same process I made this block with.
http://www.procooling.com/index.php?...icles&disp=128
Base thickness depends on what kind of flow rate you are going to try. High flow rate thinner base, low flow rate thicker base.
I find about a 4mm base is pretty good over all. Any thinner and I worry about flexing on some designs.
Think surface area more than turbulence. The more copper to water surface area the better on these types of blocks.
I was thinkng the samething on the rad as ben. 1 rad that has 3 120mm fans.