Spider_Man, you need to explore the website. Most of the information you are looking for is there for you.

There is a description of the engine, what you can do with it, how much each version costs, what each version's features are, etc. The demo is free to download. Try it for yourself and see what it can do by following the tutorials, looking through the manual and having a play.

You will get a much more clear view of 3D Gamestudio by doing this than you might think. You'll see instantly that you can design levels to look how you want them to (I think this was one of the things you were asking). You'll see that the templates are free. You'll use some of them in the tutorials.

Use the links at the bottom of this page. I'd recommend starting at the info page, then go to the download page and get a copy of the demo and tutorial. While you are downloading the demo, have a look at the what else is on that page and the rest of the site.

Once you have started with the demo, this forum can be a great place for help. Until then, it's all a bit abstract. Some things are just easier to DEMOnstrate than describe.