1) Fps Creator doesn't support Co-op
2) Again, doesn't support Co-Op
3) Fps Creator only supports First Person View
4) Check this out:
http://forum.thegamecreators.com/?m=forum_view&t=130281&b=24
5) I don't really get what you mean.
6) To me, It sounds like Fps Creator is not what you want, for the type of game you are trying to create.
I dont have any of those packs but from what I have heard, pack 18 is pretty good.
To answer your question from the other thread. You can use models from Model Packs in other projects. I dont know if you can use the stock models that come with the engine.