I agree totally with Sugarcat, biting and grabbing is totally normal and had kitty been left with littermates a few more weeks, he would likely not be so bitey and grabby with the claws. I may have the same issue with the kitten I picked up as a stray. Don't know how long she got to stay with mom but right now she's pretty gentle and while she'll hold with her paws, her bites are more like little nibbles. If you can find your kitten a decent sized stuffed mouse that he can grab and hold onto to kick and bite that should help. When he starts getting a bit rangy, give him that to bite.
I also agree with the 2nd kitten...they're so much more fun when they have a playmate.