Wow, that world looks amazing!
The lighting is pretty easy to fix. At the minute there is no 'vertex lighting' applied. Actually, all the vertices are set to 'grey', which is why at appears dull. MAX adds its own lighting, as you can see shading in the viewports. The solution to make it nice and bright:
Add a vertex paint modifier to the areas/nodes you want to brighten. Choose white, and paste on all. Collapse the modifier, then re export (you wont have to re export the textures).

- vertex.JPG (17.42 KiB) Viewed 1730 times
Hope that helps. Thanks, Rob