ConTeXt project structure?

[Gerben Wierda <Sherlock@rna.nl>]

It is probably my lack of brain cells, but I do not understand chapter 
2 of the ConTeXt manual at all.

Suppose I have a manual-like document and I want to produce different 
PDF-files out of it:

1. The book
2. The book in another layout
3. The book in screen format with navigation
4. A simple presentation with bullet points, one or more pages per 
chapter

As I understand it I will need 4 environments:

	.../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

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

etc.? Or do I use multiple environments in one project and I can get 4 
PDF's as a result? Or are these multiple products (I would guess this, 
but how then to set it up)? Should my chapter files contain 
\startcomponent \stopcomponent and does that mean they are 
independently compilable?

I have been reading and re-reading this, but the relation between 
project, environment, component and product keeps escaping me.

Is there a good example somewhere?