A guy on youtube tested the "cats don't walk on aluminum foil" theory, as it turns out, if a cat wants something that requires walking on aluminum foil, they'll more than happily do it.
As for the kittens getting on the counter, hiss(sounds like : tssssst!) at them and take a heavy step toward them, or hiss at them and loudly clap your hands.
Science Diet is TERRIBLE food. As far as how much to feed them, the thing with feeding them dry food like Science Diet, is that it is so poor quality that cats(and dogs) feel like they need to eat more in order to feel full. So they eat more, and more, and more, when available, and gain the pounds. If you feed a more nutritious food, they'll eat less and feel full faster.
You can pour food in and let them eat as much as they want for 15 minutes, and then take it all away until the next feeding. Or you can experiment with different food amounts until you find one that seems to work.