Hello,
This is Dr. Christian. Welcome to JustAnswer. Their eyes and ear will not open until about 2 weeks so until then mom will help them urinate and defecate. At about 3-4 weeks they might start trying to scratch and use litter. Typically kittens start to be weaned by the mother around 6 weeks at which point some soft foods can be offered. It is possible for 4-5 week old kittens to start eating small amounts of soft food but they should still be getting mother's milk too. If you have more questions please let me know.
Veterinarian
12 years of veterinary experience in medicine, surgery and behavior with exotics,canines and felines