1. I am interested in rewriting urls at runtime, because the languages and parts of the urls should be configurable by an user in the administration backend. So parts should be loaded in the beginning of an request from the database and put into the rewrite mechanism (in- and outbound links). Is there any way?

Example for mapping with en, de, catalog and katalog as dynamic url parts:

/en/catalog/myname.html -> /catalog.seam?id=myname&lang=en
/de/katalog/myname.html -> /catalog.seam?id=myname&lang=de

2. What is best practice setting the seam built-in locale from the lang request parameter in the beginning of an request? Do you have any hints?

Thanks for your help!