Since this game is about destruction and physics later on in the development of the game will you be able to crash down buildings and knock down trees and things like that?
This has been discussed before. Many, many times before. Try to use the search bar to answer your questions before resorting to creating a new thread. The short version is "no." The physics can theoretically be used to create whole buildings, bridges, and trees, but the engine is targeted specifically at soft-body physics (smashing things up rather than tearing things apart), whereas cracking open boulders and knocking holes in brick walls is the territory more of rigid-body destruction systems, like Havok destruction or Nvidia APEX. At most, you can expect road signs, barrels, and fences to be destroyable (IF sleeping is implemented), alongside a myriad of vehicles.
Not entirely, Physx is the whole of Nvidia's physics system. APEX destruction is a program of that physics system that allows for mass rigid-body fracturing, like so: I had more interest in expressing just the latter. Just so I'm not misconstrued, I'm not stating that this is in any way compatible with BeamNG.