Smr Simple!

When purchasing a train to only move raw materials from a coal mine farm, vineyard to a town or city, is it more economical to leave the trains composition in place for the round trip or to remove the freight cars for the trip back to the supplier?

I have a steel factory which is profitable and a war factory which is not using the steel...I seem to remember this having worked in other games...what am I doing wrong?

Is it possible to sell an unprofitable one in a single player game?