few more docs

Hi,

although I might touch these sources again tomorrow, I thought it's good to open a PR in order to receive early feedback (mostly of crude type about missing pieces/paragraphs). Yet, any feedback is welcome :)

tia, F.
Yeap, this is the kind of feedback I wanted today, very good bunch of bits overall!

I've addressed much of it with fresh commits, I am diving to some of them in comments below.