Filtrar coluna XML no SQL Server

Para filtrar conteúdos

Gerando conteúdo

Obter o valor da coluna do XML

Fontes:
XQuery for the SQL Server DBA: XPath
http://www.allaboutmssql.com/2012/09/xqueryxpathxmlschemaxml-index_6.html
http://stackoverflow.com/questions/19940566/xquery-value-value-requires-a-singleton-or-empty-sequence-found-oper/22711296