Yes, a loveseat sofa beat would be safer, as a futon has nothing to keep someone from rolling off. Also, a loveseat sofa bed normally takes up less space.
IT depends on how the person driving the car is handling it.If the person is drunk, then no ATVs are not safe for small children, but if it is a good driver, then yes ATVs are safe for small children.
Yes, they have a Lego duplo kind of set. If your child is less than three years old, you should get Lego duplo. If your child is less than a year old, you might want to get Lego quatro.
I would use a flashlight to be the sun, and a baseball or similar ball to be the earth and just do a very laymen term demonstration, that way they can see the shadow the flashlight casts on the ball...