I can only answer the first question on a basic level because ive only seen one other person with a gun(all ive basically done so far is server hop at gun drops and collect a shit load for my global inventory + murder a couple dozen people with basic gear). However, I think someone shot at me with some sort of high powered rifle and it scared the fuck out me. I could definitely hear where it came from and the shot echoed through the forest from it's origin. Theres definitely some sort of 3d sound implemented, but ill say from my experience si far its less impressive than dayz. The sound in dayz blew my mind at times.
The draw distance seems to be really far. I was scoping in on a town from a considerable distance and could see little zombie specks roaming around.
Im not positive of any of the building stuff is implemented yet.
