I can only answer the first question and part of the third:
It is easy to add equipment using the equipment editor (download here: http://homepage.ntlworld.com/a.edmiston/toaweqpedit.htm), but of course you will have to determine which values to plug in.
I think the terrain is the same in COW as in TOAW III. According to Wikipedia, the Dasht e-Kavir looks like this: The desert soil is covered with sand and pebbles; there are marshes, lakes and wadis. The marshes, lakes and wadis are available terrain types, but the desert itself could be trickier. There are clear, sand, and dune terrain types, but none of these might really be appropriate for a hard, flat, desert (if that is what the Dasht-e Kavir is).