World creation

#1 In newer engines, detailed mesh is used for scenarios, and they are all exported direct from max. Not Torque, thought - it's engine is a little different, outdated, but if well used it can become quite good.
In the standard Torque engine, you have three types of objects:
1- terrain and other special scenario objects, like clouds;
2- .DTS shapes, created by 3Dmax;
3- interior .dif blocks, created by quark. They use a special mapping procedure called BSP. They are very light.

Dif blocks will render faster and will be lightened faster and better than any DTS, but if you choose to create one single, huge dts model to be used as the world, is your call. There will be no shadows on it, it will get a slow framerate and god knows which other problems you will encounter. The collision blocks should take care of the colisions and such, but a warning: i tried recently to make some stone-rendered temples, very small ones, and even so they got heavy enough for me to drop the idea.
The game world is a intelligent mix of dts, dif and terrain - if you try making everthing in just one kind, either you end up with a slow or bad looking world, or both. Get used to Quark and to the Torque terrain editor, it will save you from lots of frustation.

#2 Thanks for the explanation. So dif is the format for creating buildings, right? My problem is that I will require very professional virtual cities to add to my game at some point and I know i won't be able to build that by myself out of mission editor and quark. Are there lots of art assets like virtual cities that I can buy to be used in torque?
thanks

#3 You will need to contract someone to create your art assets. You can use content packs like those from 3D Diggers, but if you cannot make them, you will need to find an artist who can.