Also, since none of these units are interconnected like in MTH, how do I get the rear, dummy A unit's headlights to turn off when going forward? Are all TMCC multi-unit engines like this? In MTH, the rear unit gets instructions from the lead so it knows when it's going forward or backward. What tells the rear unit in TMCC that it should be off?
I think what you want to do to make the headlights directional is to "Build a lashup"
of your engines as described in the manual they came with.
In TMCC mode the front engine will light up when going forward. The rear engine lights up when going in reverse.
I'm not sure if you can do this in conventional mode.
See this chart for instructions to make a lashup.
Hope this helps.
Mark