Vehicles - Import the mesh to BeamNG and make a whole new N/B skeleton. Terrains - Get the height map or the .ter file and import it to BeamNG.
I'm not exactly sure what you are asking, but any mod for ror will NOT work in beamng. Sorry. edit: unless, like stated above, you convert the mods
No. Porting mods from RoR is quite a bit of work, especially with vehicles. I don't think anyone has actually ported an RoR vehicle to Drive. If you wanna use RoR mods, then use RoR.