Properly Create and Serve PDF Blob via HTML5 File and URL APIs

Ok, Let's say I have document data stored somewhere, let's arbitrarily take this pdf.

Issue #1. What I want to do is make an AJAX call to this URL (because I need to pass some authentication headers and it is cross domain). Then take the returned data, create a blob url for it, append an iFrame to the DOM, and direct the src to the blob url.

Currently my code looks like this:

$.ajax({
  url:'http://www.grida.no/climate/ipcc_tar/wg1/pdf/tar-01.pdf'
}).done(function(data){
   var file = new Blob([data], {type:'application/pdf'}),
       url = URL.createObjectURL(file),
       _iFrame = document.createElement('iframe');
      _iFrame.setAttribute('src', url);
      _iFrame.setAttribute('style', 'visibility:hidden;');
      $('#someDiv').append(_iFrame);
});

Unfortunately, I am getting a 'Failed to Render PDF' in the iFrame.

Issue #2. I'd like this to result in a file download prompt. Not sure how to guarantee this given that PDF's will naturally just display in the iFrame.