As far as populating memory goes the downloadable manual should go over this, each socket should have the exact same memory layout with installed sticks, you will have to install them in sets of 4 of what ever capacity you decide on and should not mix capacities up, 4GB sticks and 8GB sticks etc., it very well could work doing that, who knows unless you try right
How do you plan on cooling these CPU's ?
How do you plan on cooling these CPU's ?