XSLT Quiz: Understanding a Stylesheet

On the left, you can see a complete stylesheet. Read the stylesheet and answer the questions.
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xpath-default-namespace="http://www.w3.org/1999/xhtml"
  xmlns="http://www.w3.org/1999/xhtml"
  version="2.0">
  
  <xsl:output method="xhtml" encoding="utf-8" />
  
  <xsl:template match="node()|@*" priority="-1">
    <xsl:copy>
      <xsl:apply-templates select="node()|@*"/>
    </xsl:copy>
  </xsl:template>
  
  <xsl:template match="span[@class='editorialNote']"/>
  
  <xsl:template match="h3">
    <xsl:copy>
      <xsl:attribute name="class" select="'topicHeading'"/>
      <xsl:apply-templates/>
    </xsl:copy>
  </xsl:template>
  
</xsl:stylesheet>