Question about semantics in Drupal

Hello,
I want to create a website which use Semantic web technologies.
So I want to know how semantics is implemented in Drupal to get some ideas. Here some questions :

1. I will use RDFa to annotate my pages, can I access them using ARC2 RDFa parser even the pages are with .php extension, or I have to redirect pages using Apache redirection rules to change the extension to .html ?
2. After annotate content by RDFa I want to create a SPARQL endpoint and store triples grabbed from annotated pages to get the ability to perform SPARQL queries ? Or the is an other idea to store rdf triples ?
3. ARC2 documentation is a little bit summarized, is there any other rich documentation ?

Thank you.