inquiring mind ...

As a holder of an MBA in Business Economics, I've been wondering about how economics relates to the operation of steam trains in the year 2001. Since several members of the C&TS Board visit here on occasion, this seemed to be a good place to ask:
1. What is the cost of hauling an extra empty passenger car from Chama to Antonito (assuming that a train is already making that trip and no extra loco would be required)? I assume that this cost would primarily result from having to burn more coal.
2. How much more would be added to the cost in #1 if the car is full?
3. How much cheaper is the run in the other direction (from Antonito to Chama)?
4. How are ticket prices calculated? Marketing must figure in here somehow, since the prices for this year show that a full coach would bring in more income than would a full parlour car (which is the opposite of what I would have assumed).
5. How would these answers change if someone (like a foundation) were to donate light-weight wooden or aluminum cars? From what I can tell, the current cars are quite a bit heavier that what the D&S currently uses.
Thank you in advance for whatever information can be provided.