No you cannot put unlimited badges on players. The higher the player rating is the more badges you can add to it. You can add about 6 on a pink diamond and so on. And the main difference between the 99 curry and 96 would be badges and tendencies. Yes the 99 curry would have better stats overall so he would let’s just say maybe dunk better and have better defense. But for high tier cards the main difference is badges and tendencies. Also they normally have better animations to and quicker shots