I've probably bought a dozen factory shop manuals over the years from most manufactures. They're all pretty good about details, including pictures. They are what the dealer mechanics rely on. The only surprise I had with the Focus manual is that it did not include "out of vehicle" engine overhaul instructions. I certainly hope to never have to overhaul the pistons or crankshaft though.
The main shop manual is about 2 1/2 " thick, the emissions manual is about the same, and the wiring schematics is about 3/4" thick. The emissions manual covers all 2004 Ford gasoline engines and contains a lot of operational theory and troubleshooting flow charts. All three manuals are about $350.