Thanks aluseus GOD, that was a useless comment. BSP can be used as worlds, but that's not what he wants now, is it?
The Dark Game engine that powers both DBPro and DGSDK doesn't really support 3DS properly, even though it's advertised as doing so. I found that using X is your best option from 3DS Max, I tried to make a DBO exporter but I gave up.
As for collision, I haven't been keeping up with what's available, so you'll have to look into that. But for a 3D file format for your world, use X over 3DS
Big whorls have little whorls which feed on their velocity,
Little whorls have lesser whorls and so on to viscosity. - Lewis F. Richardson
Also, my website has no content. But it looks perty