Here is how this should be made for simplicity. If Hero Factory joints are used to create the spiral skeleton, then the HF armor can be used for the back. The problem is, this leaves no room to attach anything on the front. If HF joints are made with more connection locations, The attaching anything to the front is simplified and reduces piece count.
The jaws are the only part that would be slightly difficult, but not impossible. An bar clip with an angled top similar to a minifig hand can solve that entire location. As for the rest of the head, Hero factory and Bionicle heads are usually premade. This situation can be the same.