Right, kittens need to be in a bed that has a low side so that they can explore the world at their own pace. Never throw food into bed, kitten bed should be scrupulously clean,yes in the wild mum would take bits of freshly killed rabbit etc to the nest but this isnt in the wild. Litter tray needs to be put very close to bed and kittens encouraged to use it once they start moving about;you do this by gently placing kitten in tray and using bit of cotton wool or kitchen towel to stimulate them to go (gently rub their bits).
food wise mum should be fed near the nest and kittens out of curiousity should go to food.
Please remember once kittens leave the nest they are fragile and get underfoot always walk with a slither rather than a step.