Sounds like your not giving the app enough time to generate the texture and morph or the you have not exported the head right.

I have used about 20 different figures and every one of them has worked in P7. I even got it to work with BJD. I got a good animie head for that one. You know what's funny? I didn't read all of the manual. Only the part about needing to export the heads of all your figures if you use Poser and the way it tells you to do this. I don't remember if it states to not export the eyes with the head but all the threads at Daz mention this.

As for clother, never needed it, so I can't have an opinion on it's worth. I do find Faceshop a very handy tool.