vet. he should be able to identify the eggs, and if she has fleas. plus, she needs to be wormed.
if she has fleas, frontline type flea med for her. if you are lucky, house did not get infested. if it did, shampoo rugs, vacuum, wash floors, then spray whole house with "siphotrol plus II premise...
4 weeks is too young, they can barely walk.
mom will teach them, but it takes a few weeks.
they all eat and play in it and even sleep in it. soon, they learn it is a toilet.
also, make sure the box is low enough so they can get in. no kitten is going to scale a wall to go potty. you might...