Woah...I'm not entirely sure that any of those are possible, and if they are it would be extremely labor intensive...such as, each piece of grass would need to be a static object, or a very small treemesh. I don't know about the blood, and what the hell is the environmental vehicle concept? BF42 doesn't support "underground", I think you can only make caves and the like by covering a hole with an object. I don't think water can be at two different heights, as the water level is specified in the init.con I believe. Waterfalls might be possible but I don't have the expertise there. Animal bots could be done, just remove their weapons/make them invisible, tell them never to fire, and restrict the AI Paths to a small area so they don't run all over and possibly get into trouble, like a gunfight. Would require redoing the entire skeleton setup of the game as well, (which I believe means everyone is an animal) unless the animal was like a vehicle
I think I saw somewhere that you can make bots say pre-recorded things at regular intervals, but I don't remember how. I know a third person crosshair is possible but again I don't know how to make it and I believe it would be very buggy.
ahhhh lot of typing