Hiya - and welcome aboard
1. There is a text file (BatLocs.txt) which gives a list of the numbers associated with each location. it can be found at ...\shrapnel games\the camo workshop\winspww2\game data\design.
2. Create and save your map as normal in the editor then start a new scenario load in the saved map but have it set to summer/winter etc.
3. dont believe so (open to correction)
hope fully this has helped a little till someone with a little more experience pops along with better/fuller explanations