sounds like a great project! Let us know when your'e done!
just a side note: from what I remember making CS maps with hammer: the Hollow tool sucks.
Look at that spiral it created for you on the first pic.
From what I remember the better technique is to section of the square into trapazoids, with the sloped side towards the inside of the whole.
it will perform better and take up less polygons....
Great work so far! I know how hard it is to model something according to real measurements! (I tried and failed to model my school for a DE_ map
)
Good luck!
-Leav