Human disease or turtle disease? Turtles can get colds and suffer from other viruses and bacteria but most of these are not transmitted to humans, at least not easily. However, they are known to carry salmonella which doesn't much bother them but can infect humans. For that reason you should always wash your hands after handling a turtle or other reptile.
No, red-eared sliders are not illegal in England.
yes, mini red eared sliders do exist
Yes, red eared sliders eat minnows in the wild and in captivity.
never
yes they can be separated because by nature, red eared sliders are solitary creatures.
no
no
Red-eared sliders typically hatch in late spring or early summer, usually between May and July.
humans
no
A Red Eared Slider can only "procreate" (have young) with another Red Eared Slider but they have been known to "mate" (have sex) with Yellow Belly Sliders. They probably wouldn't try to mate with any other kind of turtle, other than a Slider.
Red-Eared Sliders are Semi-Aquatic turtles.