A lot of that looks pretty awesome, though I have an objection: the characters are way WAY too powerful. Giving them 15 HD, regardless of what those HD are (even commoner) means they are mythical in power, and far greater than anything the world has ever seen.

For instance, any of them would be able to survive a 500 ft fall, eat deadly poisons for breakfast, fight numerous heavy weight boxing champions at the same time and win easily, and be better at any skill they put ranks in than any human who has ever come before them.

And they would do that all in human form. Once you add in morphing, it would become utterly preposterous.

Now I know your intention was to make a base class that translates to DnD-type power, but I think the morphing power or being an animorph would be better represented with an acquired template. The template would give similar abilities to what you outlined in the class, but would provide virtually no benefits when the character was not in morph.