Welcome Smalltowngirl! It sounds like you have a really fun kiddo. At this point, it's hard to say whether he's gifted or not based on the info you gave us, but he has some gifted traits (like the wanting to learn everything there is about mummification at age 4). I think you shouldn't worry too much, but rather try to follow his lead about what he's interested in doing. Is he having fun at school? I'm not sure there is really anything you can keep your eyes on beyond what every parent does -- if he seems unhappy or underchallenged, you will probably notice this and seek out the causes, one of which might be that he is ready for more.
My son also didn't like anything to do with writing, and he still doesn't. I didn't try to make him learn to write before kindergarten -- that is certainly one thing kindergarten is perfect for!
