The sequence of work operations is (as far as I've seen) always done by the "programmer", as in the person using CAM or text editor to write the g-code program the CNC machine executes.
I've looked around, and haven't come across much for books. There are a few open source attempts at path generation, and that's what I'd suggest for reference. FreeCAD's path workbench can generate a number of paths.
The other thing to look at is most (all?) pro-level CAM software write the tool paths to an intermediate format that is the "post-processed" into the final output format for a specific machine. The intermediate format is called APT. There isn't much on the web about it, but there is an open source project on sourceforge called aptos that has an implementation of APT.
