Very few cats have been selectively bred into what we call breeds. Most cats just breed freely without any humans involved. So most cats (95% +) don't have any breed background at all, not even a mix. So unless he's registered from a respectable breeder, he's a domestic shorthair, which is what we call cats with no breed (or domestic longhair, depending :tongue2. He (or she?) is adorable!
If you got Oreo from the pet store, he may already have been sick. Even Silver looks a little young to be away from his mommy. He is a tabby (maybe a long hair, you'll be able to tell as he gets older). Has he been to the vet's yet? You should probably get him an appointment, just to be on the safe side.
Oreo's story is why adopting from a shelter is usually better than buying at a pet store. I am sorry he died.
Two months old - that would be eight weeks and he looks about six weeks to me. WAY too young to be taken away from mommy. While he can eat on his own, he hasn't learned important lessons about how to be a cat, which you will have to teach him. For instance, he may need to be taught how not to play rough- he may use his claws and teeth inappropriately. His mom and siblings would teach him that during playtime.