As reported in another thread, I've received the AT&N Consolidation DLC, which downloaded after a few days' delay. Now I'm starting to learn how to drive it. The extensive users' manual provides a lot of information. I'm sure that all of it will eventually become useful, but I'm still trying to absorb it all.
I started by trying the "Extended Tutorial for Expert Mode" and quickly ran into two very real difficulties: darkness and instructional pressure. I simply could not see most of the detailed cab's interior and thus could not carry out the instructions, which came at me much too fast. Backing away a bit, I quit that scenario and tried one of the free-roams. That gave me more time to search for various cab controls (learning, along the way, that opening a valve handle with the mouse means dragging to the left, not to the right, which is the correct direction of rotation), but my major problem was still the murky darkness in which several start-up steps must be carried out before the cab light can be turned on.
The solution proved surprisingly simple: increase the overall brightness. To do this, start TS2013 and follow this sequence: Main Menu --> Game Settings --> Graphics; then adjust Screen Brightness. I raised the level to 37, which improved cab interior visibility quite a lot, but each user will have to find the most suitable number.
The new brightness setting allowed me to actually see the various valve handles, levers, etc. that should, ideally, be manipulated by mouse. The manual also includes a lengthy table of keyboard controls, and I've started combining those with mouse maneuvers. Still working within a free-roam scenario, I've actually managed to get this extraordinary locomotive moving down the track. As I discover other tricks and tips, I'll add to this thread and I hope that others will do the same.
Please do not contribute if you do not already own this DLC and have already tried driving it.