Regarding the debris issue, the Adam Air flight that crashed in Jan 2007 between Borneo and Sulawesi (sp?), the debris wasn't discovered for a good 7 - 14 days after, and that's a narrow strait between the two islands. So a crash in open ocean, the debris could take weeks (or even never) to turn up.
With the Air France crash, the ACARS data helped very much to pinpoint where to send the search planes to look, and the first items were discovered within a couple of days. Obviously, with ACARS switched off in this flight, they can't go on that data. I reckon the perpertrators in this case would have studied the reports of the AF447 crash meticulously for ideas.
Also, there was a cargo flight that totally disappeared over the Pacific between Japan and Brazil in the 70's with a priceless load of Japanese art that not a trace of has been found.
You can really see what my reading matter has been this past week 