Question

For phonegap development:

1. is it possible to fetch remote data for phonegape?
2. is it possible to fetch remote json/xml file using ajax/jquery ?
3. XmlHttpRequest can fetch remote xml file ?

also any suggestion for it or important link.

Answer 1

Ajax works no different that it does else where execept that cross domain calls are ok with phonegap,
see my other answer

Example of jquery ajax call @ http://api.jquery.com/jQuery.ajax/
Parsing xml with javascript @ http://www.w3schools.com/xml/xml_parser.asp

$.ajax({
  url: "test.html",
  context: document.body,
  success: function(){
    $(this).addClass("done");
  }
});

Example of native javascript call

Ref from phonegap about ajax
(see question:

Q. I want to create an application for phonegap to access externally deployed web services via AJAX. How can i resolve the issue with the cross-domain security policy of XmlHttpRequest?)

True to life example on this site

This should be enough to get you started.
Let me know if you have any other questions.