1) Is the list of of commodities demanded by various cities in any particular order? I always wondered if the cities higher on the list had a bigger payoff than those lower down. True or false?
I've also always assumed that the trade list is in order of descending profitability level; I've nothing other than vague recollection to substantiate that though
I'm quite sure this is not the case, unless something changed for TOT (and I didn't notice it while playing Imperialism). In fact, it
can't tell you what is most profitable, since the calculation depends on the distance between the source and destination. (Well, it
could when you open the window when deciding what commodity to choose, but I doubt they implemented two versions of the supply and demand window.)
2) How do you make the construction time to build a railway longer than for roads? (for another project)
I believe that if you increase the terrain movement cost, it increases the cost of building roads and railroads. So, I suppose you could double movement costs and allowances. I don't think there is a way to change the costs of roads and rails in the rules.txt, though I haven't checked, and others would know much better than I would.
The natural way to increase the cost of railroad construction with Lua would be to take away some of the accumulated settler 'effort,' but unfortunately we don't have access to that number (it is the same number that determines how many turns aloft a plane still has).
It is possible via lua events to place railroad, so you could have a system where a town builds a 'railroad building' improvement, and the town tries to link up with a neighbouring town, or something, via event.
You can also give settler orders to units via events that they can't otherwise do (even to non-settler units), so you could withold the railroad tech, but still allow a specific unit to build the railroad (though you'd have to put up with some contradictory text boxes). I only did brief experiments with this, and that was some time ago. This would preclude the AI from building the railroads, however, unless you give event input to their units.