From what I can see, the winch came off a civvy Rover (sorry, no clue if it came off a 2a or 3), the angle iron at the lower front would have run along the top rear edge of the bumper.
The first bullbar looks like an original military unit, whereas the second bumper is a civvy ring-in. Personally, I'd fit packings under the front of the winch brackets, then refit the first bullbar, though it won't then be concours. Just a note, is that bullbar twisted or am I just seeing it wrong?
A fairlead is the rope guide on the winch, whether by rollers or a rounded corner. It's to stop the rope/cable catching and becoming damaged, and helps keep the spooling neat.
Feel free to ignore my advice if you need to - I'm a sheer amateur in military Land Rovers.