when they can leave depends on the size of the litter, a litter of 3 for example can leave as early as 3 weeks while a litter of 6 may not be able to leave as late as 6 weeks, the basic thing is when the males start rumblestrutting, its time to seperate(rumble strutting is growling sound, and wiggling their bottoms) male and female are really not to difficult to tell apart, the males will be shaped like an i while the females will be shaped like a Y, guinea pigs can be sexed right after birth. yes piggies CAN be spayed and neutered however this is VERY risky. the mom and babys should both be eating alfalfa hay, while the babys are young make sure they have unlimited pellets.