Create document sets in Sharepoint 2010
http://sharepointdon.wordpress.com/2009/12/05/how-to-create-a-document-set-in-sharepoint-2010-beta/
http://blogs.technet.com/b/vedant/archive/2010/04/21/using-the-document-set-feature-in-sharepoint-2010-part-1.aspx


Create document sets programmatically in Sharepoint 2010

http://code.msdn.microsoft.com/office/SharePoint-2010-Creating-41d2aa7a
http://www.directsharepoint.com/2012/01/creating-document-sets-by-sharepoint.html
http://howtosharepoint.blogspot.co.uk/2010/12/programmatically-create-document-set.html


Document metadata
http://stackoverflow.com/questions/12474940/adding-metadata-while-uploading-documents-to-sharepoint