Most tutorials found for P6 and P7 are applicable to P8.  Hair tutorials come in 2 flavors, dynamic and conforming (figures or props).  Take your pick.

At the moment, Faceshop will not give you what you would expect.  There are other threads on the topic running currently.  Most users are not satisfied (including me).

Elaborate further by about girlfriend transformation into a Poser figure.  It would take a combination of morphing the base figure and generating a 2D texture map with your girlfriend's features to accomplish this.  It can be done but it will take plenty of trial and error.

Do you have V4 installed and did you validate and update her files?  She should be found in your figures folder of the library under DAZ people.