I am not sure how I am going to stop the drives from moving around, maybe some kind of flat metal spring to put a small amount of pressure on the hard drive to stop it from moving around, ill cross the bridge when I come to it. I have no plans to use a back plane; just cables. I think the lightly hood of a fire is very remote so I am not really worried about making it fire safe. I was thinking of using conductive paint on the inside of the case for some electromagnetic shielding, the case is going to sit in a metal server rack which will also provide some protection.