You don't understand. I have some decent rankings but when yuou dissapear from the SERPS alltogether all the keywords that drive traffic vanish. When they come back they usually do so in exactly the same positions or thereabouts.
Always best to check backlinks in Yahoo as Google never shows the true amount (although they know they are there and still have an effect ) Quick check in Yahoo shows a good 1700 links in so not doing badly. However I'd agree with some of the other comments here about targetting search terms which attract traffic. Being #1 for a low or no-traffic term is nothing more than something to boast to your mates about - but it will earn you very little $
Yep, as long u have original content plus good backlinks, should be okay later. Don't worry too much.
its not always the case of disappearing then reappearing upto a week later, recently many have experienced drops for a few months, with no major chnages being done, luck of the draw