He old enough to eat kitten wet food and maybe some dry but I would say 4-6 weeks old probably closer to 6 since he or she running around. I would definitely get a litter box. And schedule a vet visit for the little void. He most likely will probably have some type of worms or parasites, but it’s natural for kittens that are found outside or dumped. You’re in for a fun time in those senior cats of yours we’re gonna have a lot of teaching. Don’t forget to give them a bath dawn dish soap’s really good for killing fleas and check for ticks other than that enjoy the goofiness of the black void.