It seems that all the head INJ morphs have to be injected before Face poses can be used. Does this really have to be done or is there a better way? Expressions are preloaded with the latest V3/M3 characters, but not shaping morphs.

Are you talking about when you save the face to the library palette? Yes, because INJ technology is not native to Poser, you can't create INJ files from within Poser itself. There are several programs to make INJ files yourself. There's INJection Pose Builder at Daz, Injection Magic at Daz (I prefer this one), and I think there's a way of doing it with Pozer's Little Helper, which is a freebie, but I've never investigated that one. You can also do it by hand, but it's tedious and time-consuming. Here's a tutorial: http://rbtwhiz.com/rbtwhiz_rScript.html

I'm trying to load a Face from the Expression Library. Without morphs previously injected, the face doesn't do anything. Faces loaded from the Poses Library seeem to work okay without having to inject al the head morphs first.

i believe that what is happening in your case is the face you're loading is really a preset of turned dials in the head morph package. i believe that once you inject the head morph pack and then load the face that you can save that face as an obj and then reload the secen without the face morph pack, then add this morph target.