I felt the need to answer your questions myself...
1)FPSC uses .X files. For stuff like enemies it's easy to put your models in, but stuff like levels can be harder. You have to cut up each piece into 100x100x100 segments then export each one individually.

however, if for some reason you don't expect to use enemies (or dynamic entities for that matter) you can export it all at once. But again, if you do that, collision for enemies will be off.
2)No, you don not install it. Fortunately there are many ways to pack it in an installer on the wonderful internet.
3)Yes, the scripting language FPI. It's okay at first, but if you get a mod, (which are okay, most noobs think they are bad, just know that TGC encourages modding to the point that they released the source code) and the library of FPI commands will expand. Trust me, FPI is the easiest thing you will probably learn.
4)Depends. If you use bad grammar and not be specific, you may not be taken well. We have too much of that now. If you use good grammar and explain your problem well to us, we are more than happy to help.
5)Yes, it's everything you need to get started. But trust me, in the future you want to get some custom media. There's tons for free on the forums, and a plethora of stuff to buy.
Anyway, good to see you here! Hope you enjoy it over at the TGC forums.