Heh, about 15 seconds after asking the 2nd question I was cutting foamcore. I realized suddenly that there was no reason that the rooms could not be used outside of the sewers, so I went with the more solid (and in my experience easier to cut) foamcore. Plus I am not sure that I have that much mattboard left.
All the room blocks are going to be the 7x7 format that I was complaining about over on the Urban Mayhem thread, with interior rooms made with IW. They are just something to do the job, and will likely be replaced after the Festival is over.
Just to give an idea of the layout this is how the basic boards go:
O--
[]O x4
O--
[][] x2
O[]
[][] x2
O--
--O x4
O[]
[]O x4
and 4 L shaped boards.
I intend to make some more basic boards:
O--
----
O[]
----
And the doubles:
O--
----
O[]
Where O is a sewer pool, -- is a sewer main, and [] is a blank floor (and where rooms can be plopped).
The (tired) Auld Grump