Those are permanant. Don't try and remove those, because you risk breaking the spoiler.
As for the rubber pieces that you are talking about, I installed an authentic TRD
spoiler not more than two weeks ago, and I don't remember any of those. There was one though, but that was only used to seal the hole that the 3rd brake light wires came out of.
As for the objects that you put in some of the holes after you drill them in the trunk, authentic spoilers come with clips that pop into the hole, and the metal spears (not the screws) go into those clips to make a secure fit. When I say metal spears, I mean that there were a few metal spear like pieces that came out of the spoiler, and served to stabalize the spoiler. The spears didn't have threading on them, so that's why I didn't call them nuts.
The screws on the other hand, require that they be secured by nuts.