Welcome! I am sure others here on the board can help you more with your questions, but I just wanted to say that just because your son isn't a fluent reader at 4 doesn't mean that he isn't going to pick it up easily at 4.5 or 5 or 6. Some kids pick it up early and quickly, some kids pick it up early and with slow progress, some kids pick it up "on time" but quickly, and all these kids can be gifted. It certainly sounds like your son is! But, too, even if he turns out to be an "average" reader, it is absolutely possible to be much more gifted in one area than another.
BTW: your son's math abilities do sound amazing! I look forward to hearing more about him in future posts.
