I think we should go the, "The moon is a harsh mistress," route and set up mining and manufacturing plants on the moon itself. Saves the cost and environmental impact of having to lift everything up from the surface. Minus the worker exploitation, of course.
Idk if anyone has actually crunched the numbers on the horizontal launch system the book uses, but in a nutshell they basically shaved the top off of some mountains on the equator and made a gigantic rail gun to get ships closer to escape velocity before boosters are needed.