Questions for someone who knows real trains: When they hook multiple locomotives together to pull a big train, does each locomotive require a separate engineer, or do they connect together to be controlled from the lead loco?
All controlled by a single engineer in the lead locomotive. Usually accompanied by a conductor. Interconnection is by electrical cables between the locomotives. The same engineer controls locomotives in the middle or distributed throughout the train by radio control. The exception might be pushers which are in place for just a hill or two.
This is assuming modern diesels. In the steam era each locomotive had a crew of three or more. And a caboose followed with two or more additional crew. There might be an additional caboose and crew depending on how the locomotive group was used. Communication was by whistle and by the intuition that comes with long experience.
Also, secondary locomotives are often facing backwards. Is there a power advantage to pushing rather than pulling?
"Forward" and "Backward" has no meaning to a locomotive. Electric motors, not transmissions and drive shafts. The engineer's cab is located by railroad preference, but not by hard rules. Most railroads prefer a short hood to the front. Norfolk Southern prefers a long hood. In reality hood location is a result of how they ended up after the last run. If all is right with the world each group of locomotives is arranged by that railroads preference of cab location so that the entire group can operate either end forward.
Edits to fix spelling and other errors.
