That one stumped me too, how to get that "do you want to save it as a smart prop" prompt. And the solution turned out to be to save the item to the library WITHOUT first selecting it from a dropdown menu. I would typically use a dropdown or whatever means to make sure I was saving only the item I wanted to save, but you don't get the prompt that way. So just make sure the intended item is selected in your scene, click to add it to the props library, and you should get that message. (I'm guessing it works the same when saving to the hair library, but hair is just a special kind of prop, so either library should work.)

As for the skull cap that won't move, did you double check that the parameter settings have the min limit as a negative number (and the max limit as a positive number)? That one's tripped me up before.

Also: is the skullcap coming from embedded geometry (geometry coordinates left in the library file) or from a reference to an external OBJ? Sometimes embedded geometry can cause problems, so I use Netherworks' Creator's Toybox to extract external OBJs from embedded geometry in both items I've made and items from others. 

One final thought that's more of a question, I guess: do you need to use a skull cap to use dynamic hair on V4? Is the idea that using a skull cap lets you more easily save just the hair? I used dynamic hair on the HW Horse to make a fuzzy Fjord, and I created the hair groups right on the figure (no "skull cap" needed). I saved the whole horse to the library and it loads into new scenes just fine. 

---

TOOLS: MacBook Pro; Poser Pro 11; Cheetah3D; Photoshop CC

FIGURES: S-16 (improved V4 by Karina), M4, K4, Mavka, Toons, and Nursoda's people

GOALS: Stylized and non-photorealistic renders in various fantasy styles