Judging by those questions, start by learning the basics of 3d modeling.
The planes I believe you are taking about are something like front, back, right side, left side, top, bottom. To locate a point in 3d space you need its location on at least 2 planes. Think of it this way: any of those planes have 2 axes on it, For the top view the Z axis is a point located at the origin, what you can see is the spatial relation between Y and X. From the front you see Z and X. In order to locate 1 point, move it to where you see it in plane one, then move it only along the remaining axis in plane 2. From 3 points you get a triangle, from multiple triangles you get models. Windows and interior are just more of the same.
When you've got something modeled, then learn how to UVW map texture to it (This is what defines the template area). The wireframe layer on a template is actually just the mapping.
The script defines the structure so that the game correctly interacts with all the different parts that you model.