I'm also kind of a Newbie, but I've been using Terragen for about 3 years (I started out with Terragen classic as a freshman in High School)
I'll try to answer your questions to the best of my ability
Terragen 2 is a program that is designed so that the possibilities for what kind of terrain you can create are almost endless (if you have enough skill) so you can edit the terrain by quite a bit and still have it feel realistic.
- If you want to create a specific shape for the terrain you're going to use I would suggest making that in Terragen Classic first, and then exporting the terrain file into Terragen 2. you can then edit more detailed things in Terragen 2
- You can insert any mountains you want in the original Terrain file that you make in Terragen classic
- You can "paint" where certain biomes/environments go, but that's fairly advanced (You could use the painted shader to determine where surface layers apply if you want to determine biomes by color or plant populations)
- Terragen 2 will draw a river for you if you provide the start and end coordinates (you can alter depth, width etc...)
- You can insert assorted geographical features by painting them in in Terragen Classic, or by inserting a heightfield shader (which you can edit to an almost unlimited degree, but can get very complicated)
- I don't think you can create contour maps in this program, although you might be able to export the terrain files into another program that will do it for you
- You can control anything you want about the camera. you can point it straight down for a Birdseye view
- Terragen 2 creates entire planets, so you could zoom in from an entire planet down to as small as you'd like to go (centimeters even) so yes
- You can alter the height of the terrain you've already created in Terragen Classic, or add a New mountain with a Heightfield shader. It would be possible yes.
- If you built the continent using a massive Heightfield shader (which would be quite slow to render) it would create a random terrain, so you could theoretically not place anything at all.
The picture I have included is the continent that I created for the project that originally got me started with Terragen. It was made Entirely using Terragen Classic.
