To do this, I believe I'm going to store the maps in XML format, with the base heightmap, and a list of all of the props, entities, etc... It's probably not the best way to handle such a task, but this is only for a school project, so I suppose it wouldn't hurt too much.
After I get home from school in about 3 hours, I'm going to implement a basic state system, I shouldn't need anything overly complicated, and then after that implement a console, and put in the base for LUA scripting. There won't be anything pretty to show, but hey, it always starts that way.
Now I get to sit through a boring lecture on overloading methods in C#. SO MUCH FUN!!!