.../foo/bookenv.tex .../foo/book2env.tex .../foo/bookscreenenv.tex .../foo/presentation.tex
and I can put each chapter in a component file, i.e. chapter1.tex, chapter2.tex etc.
.../foo/chapter1.tex .../foo/chapter2.tex
You can do this. It might be worthwhile to think about making the chapter a product, then you keep the possibility to add components if the size of the chapters is too large.
I won't do that...
But here my understanding stops. - Should I create a project file for each of the 4 modes above? And put these in different subdirectories as in:
.../foo/book/book.tex .../foo/book2/book2.tex
No, use modes in the environment file.
Or use products if the content is very different.
Is there a good example somewhere? Whether is is a good example you will have to decide...
Perhaps have a look at my ConTeXt tutorial (german), it uses the structure. Link below or directly http://www.ramm.ch/fiee/texnique/material/fiee_source.zip Grüßlis vom Hraban! -- http://www.fiee.net/texnique/?lang=en