1. Yes. Instead moving the units around, move their shields
You can do this easily in the unit editor of FW, or with a paint program. The positions of the unit shields can be influenced by moving the blue dots on the green border around (make sure you use the exact color). Please, see this link to the ScenarioLeague Website for more details:
http://sleague.apolyton.net/Guides/sldt_ag_art.shtml
excerpt: "The blue dots on the sides of the square are important; they tell the program where to put the shield."
2. Absolutely. Simply create the map as you wish. If you want to have other terrain graphics later, you have to change the files terrain1.gif and terrain2.gif (or .bmp). Editing these files only changes the appearance of your map, not the terrain values (e.g. food, trade or defense boni)