Are you meaning for the general posing of DOA models, or as a material source for modding characters?
I haven't used DAZ in a long time, but I'm pretty sure that it lacks support for importing FBX format, it can import a static OBJ though.
Regarding XNALara, are you saving them to the pose folder? I find that after saving a scene, it will often load scenes folder instead when going to save a pose, it might also do this when exporting an image or OBJ file, so I suggest checking those folders. If that isn't the problem, you might have to re-download the program, if so, try saving it to a different directory, like 'C:/XNALara', so that it's pretty easy to locate.