metadata generation

[Jeff Masiello]

I know you can go to Shibboleth.sso/Metadata and dl that file to give to the IdP. A couple questions...
Is that information based on a template and if so can I modify it to include things like organization information automatically?
Is it common practice to allow the IdP retrieve the Metadata from the SP via that handler and vice versa or is a manual method preferable to exchange that information? 
thanks

Jeff Masiello