Behold A very VERY detailed tutorial on photographing your miniatures. It is a very VERY large file, so wait untill it downloads And, if i missed anything, please note me. This is, after all, my second tutorial ever
it's a type of epoxy resin called Greenstuff. Games Workshop sells it, so does GaleForce 9. There are many variations of this epoxy based on how moulable/hard you want it. There's Milliput in various thicknesses, there's Graystuff of other manufacturers, even some housework "glue" epoxies can be used as sculpting material.