This is really fantastic. I really hope that you can stay away from Vicky 3 JCM morphs (like for their collar down, shoulder and others.) They are unpredictable and makes it a problem when creating conforming clothes. I love the idea of a seperate bone for her breasts. Perhaps you can make it remote control by her shoulders.

Also, have you tried modeling the fiure not in a T Pose? The shoulder bends better with the arms are down when the original model isn't in a T Pose and doesn't make that round bulge like most Daz's figures. The worst is Michael 3.

Lastly, can her legs be longer. ;)

Beautiful work!