I gathered this info from other parts of the fourm. If you haven't already looked through the fourm for this info, you can just read this...
1)Rob k said
Quote: "Difficulty will of course be user-selectable when you create the levels."
Yes
2)Don't know... but I don't think the gun you are planning to make will be extremely huge. Plus if I'm not wrong, one of the weapons that comes with FPSC is a rocket launcher and normally rocket launchers are pretty big.
3)Not sure, but I don't think you can use turrets.
4)Richard Davey said
Quote: "A Radeon 9700 card will be more than sufficient to run FPS Creator. You will of course need to have the drivers correctly installed and DirectX 9.0c too."
I don't know what your system specs are, but if it is really old, I wouldn't count on it to work.
I hope that answered your questions pretty good Evarcha.