One thing to remember about using composites and favorites. If you make a bunch of walls in one pln, then open a new pln, those walls want be there on there own, even if they show up under favorites.. (you would also need to load you Favorite file as those are pln specific. I typically keep a running Fav file, and every time I create a new fav I reexport that Fav file ("myfav.prf") to a designated folder of exported list and other .xml files for AC). I also keep a template pln open at all times, and use that to make or adjust an composite wall I regularly use. I will actually make a new one in that, and not the pln I need it for. I am regularly updating my files with by opening Attribute Manager and loading my template file and overriding the composites. Some people on the forum say you should never override but append. It can create trouble, but if you are consistent you'll generate a vert good work flow and all building types will share common components. This might be more important fro me that the average user as I deal with stock plans. But, I know this works and builds a complete template in the long run. I have files started in 4.5 that are now running smooth in 13.
So, use Attribute manager to integrate many composites to a new pln, or keep a developed template(S) to start with. You can also copy/paste composites into your new pln. Use Favorites to access composites that are already in that pln.