Sorry to take the topic off of Zbrush, I didn’t mean to do that.
Rey bustos class is not necessarily a sculpting class. Its an Anatomical study of the humans and all creatures alike. He’s not a sculptor and no one has to be to take his class. I would recommend taking his class or just talking to him via email. The DVD him and I are producing is a reference and should visually answer a great deal of your questions.
The only last thing I can suggest is about your female with the arms raised. Here is a drawing Rey did of his model Sarah. Look how the muscles are more closely together and gripping to the bones. Here is the thing about Zac’s statements, how are you going to associate muscles without names? Calling things shoulder muscle, back muscle and chest muscle doesn’t go very far when you are designing something like a creature or rigging a character.