Matthias,
I think if the Nucleo needs lots of documentation we need to put it as PDF's in the variant folder, as the GitHub wiki is not like mediawiki as it doesn't have lots of features, and I'm not sure if I can upload images etc without putting them in the main repo
Probably the best approach is to add a docs folder inside Nucleo variant and then in the wiki put some basic information, but refer people to the PDF's
Re: USB Mass stoage
very interesting
I may have time to try that later, but I need to get back to work now 
(its 10:29 am here)