Quote: "I am completely new to DB and would like some view from all you very helpful people out there."
Well, being completely new to DB I unfortunately would advise you didn't start right away with a terrain, bushes, mountains and water. It sounds a bit like Far Cry in a way (Or a golf game like PGA). Far Cry will have been built by experienced programmers. It's never anyone's dream to start simple, but it's always the best approach...
Trees and bushes would probably be built with a 3D modeller, and then loaded in with
load object and positioned with
position object and so on... A mountainous terrain can also be built with a 3D modeller, or like you correctly suggested, a matrix.
it's been years since I've used matrices now, but the general idea is to use
make matrix then assign the matrix a number, a number of tiles length-ways, an other number of tiles width-ways, how long each individual tile is, and how wide each tile is...
There's more on it in the matrix 3d section of the help file. if it makes no sense, you're probably trying something too complex for now. in which case it would be better to start a bit lower...
It's probably not what you wanted to hear, but it's an unfortunate truth that many users expect to be able to make top-sellers instantly...