Connect the devices to your computer and restore them via iTunes. Hopefully, you've made a recent backup. If not, anything that didn't come preinstalled will be deleted FOREVER, excluding things purchased via the App Store, iTunes Store and iBook Store.
It is my understanding that the Space Gray iPhones have the black background with white apple logo at boot up and the Silver iPhones have the opposite (white background with black apple logo). I dont know about the Gold. I remember reading about that here back when the 5S came out.