Vocabulary description data

Hello,
I gathered some questions when reading various documents on the web so
here goes some of the most pressing...

Due to decentralized nature of the web (and world) there will be created
many RDF vocabularies, majority of them overlapping...
To be able to make the information most complete, solution had to be
developed to help linking of data on WWW, to build more signposts in the
City of WWW...
The solution are vocabularies defining relation between various RDF
vocabularies - RDFS and OWL,
here I see one problem - the number of vocabulary describing
vocabularies cannot grow, or we can recurse to infinity (describing
vocabulary. which is describing vocabulary, which is...) - this needs as
few as well established standards as possible.
The second (the main) problem is sharing the information.
All data in semantic web can be anything - just triples which were
publicized on some web-server... Anyone can say anything....
Anyone can say that he thinks that this term in one vocabulary is
equivalent to other term in other vocabulary (not only the creator of
the vocabulary, else the number of vocabularies will increase and they
won't be really well linked) for example...
I see need some mechanism to crawl the vocabulary description data (and
to decide credibility).
Then it will be possible to infer RDF data from WWW to preferred
vocabularies and use it.
Was there any research on this topic?
What is the status of the development in the trust area?

Regards,
Jiri