SalmonKid> In general each stage should have elements added/growing, not disappearing. I guess it should be okay if you'll add enough other changes between stages. You could try with short hair at the beginning and then "melt them into head".
Tiamat> I'm not sure. When was it released... 2010? Guess it would depend on how different you'd make them. If you'll copy the whole designs it will be copyright infringement, but if you'll make a blonde guy with pale skin and blue eyes, but with different clothes design, hairstyle, named differently etc then it should be all right?