There wouldn't be much point to rendering the terrain in Max, unless it's just as a shadow and motion matching target. TG2 will render terrain far better.
For the terrain you can export a .ter terrain file which can be imported into Max by certain plugins (or converted into another appropriate format). You can also export as LWO geometry, which Max should import. There are a number of threads throughout the forums on the subject - try the Advanced Search abox.
The textures cannot be exported officially at this time. You can do render of the terrain from directly above with flat lighting and 0 atmosphere and then use this as a drape texture map on your imported terrain, but the results will not be very good without extremely high resolution, which would make the render in TG2 faster anyway.
You can use the the Emec Studios 3DS Max plugin to exchange camera data, or use the .chan file format, which TG2 can load.
- Oshyan