XPathNSResolver doubts

Is a XPathNSResolver returned from createNSResolver be live or static ?
http://www.w3.org/TR/DOM-Level-3-XPath/xpath.html#XPathEvaluator-createNSResolver
See attached tc1.html

Which uri should a XPathNSResolver return if there are 2 nodes in the dom  
tree with different uri but equal prefix ?
See attached tc2.html
I assume it returns the uri after matching the first node in document  
order.

Thank you.